The Godzilla series is a kaiju franchise made by Toho. It features Godzilla, Rodan, Mothra, King Ghidorah, and many others. Like most franchises, Godzilla has several different continuities and spawned many comics, mangas, games, TV shows, etc., so, the canon can be confusing.
Showa Continuity: The first Godzilla film began the Showa era of the kaiju industry, with Godzilla being the usual kaiju affiliated with this era. During the beginning of the Showa era, Godzilla was mainly antagonistic in nature, taking on the likes of Anguirus and Mothra. By the time of Ghidorah, the Three-Headed Monster, Godzilla adopted what would soon become his most famous image: a heroic monster, battling terrible villains with other monsters by his side. Toho produced a significant number of tokusatsu television programs in the Showa era, one of which, Zone Fighter, even featured appearances by Godzilla and some of his other monster co-stars and is considered part of the official continuity of the Showa Godzilla films.
Kiryu Saga Continuity: * Godzilla Against Mechagodzilla and Godzilla: Tokyo S.O.S. - These two films are the only entries in the Millennium series to share continuity, and are often collectively referred to as the "Kiryu Saga." Godzilla Against Mechagodzilla is a direct sequel to the original Godzilla and establishes that Godzilla first appeared in 1954 and was killed by the Oxygen Destroyer. The only change from the events of the original film is that Godzilla's skeleton remained intact instead of being disintegrated. This film also references the events of Mothra and The War of the Gargantuas, including stock footage from both films. The next film, Godzilla: Tokyo S.O.S. is a direct sequel to Godzilla Against Mechagodzilla and makes further references to Mothra, even featuring the character Shinichi Chujo. The events of the film Space Amoeba are also referenced when the corpse of Kamoebas is found on a beach. It is also mentioned that another Kamoebas was seen sometime in the 1980's. Supplementary books for the film establish that the events of several other non-Godzilla Showa era kaiju films occurred in this continuity, including Rodan, Varan, Gorath, Atragon, Dogora, Frankenstein vs. Baragon, and King Kong Escapes.
Heisei Continuity: The Heisei series of Godzilla films lasted from 1984 to 1995, and has also been nicknamed the VS. Series (VSシリーズ) in Japan due to the word VS. being featured in most of the films' titles. The Heisei series follows a different continuity from the Showa films, ignoring every movie except the original 1954 Godzilla. The Heisei series ran for a total of seven films, with the last film, Godzilla vs. Destoroyah.
Rebirth of Mothra Continuity: Mothra received her first standalone film since the original Mothra in 1996 following the temporary close of the Godzilla series. The Rebirth of Mothra trilogy lasted from 1996 to 1998.
TriStar Continuity: GODZILLA begins with the fishing trawler Kobayashi-Maru being pulled beneath the waves by an unknown force. The French government concludes this to be the work of a huge monster spawned by their nuclear testing in French Polynesia 30 years prior. The creature makes its way across Panama and swims to New York City, where the American military finds itself in an urban conflict theater as it tries to destroy the monster. Dr. Niko Tatopoulos worries that the monster, dubbed Godzilla, has reproduced asexually and that its offspring could overrun the city. Now while the military fights Godzilla in the urban landscape, Nick and the French secret service venture below the city streets to find Godzilla's nest before it's too late. In the series, Godzilla (the baby that survived the destruction of Madison Square Garden and hatched from the egg at the end of the 1998 film--often nicknamed Godzilla Junior or Zilla Junior by fans) battles a large group of giant monsters. The show tracks Godzilla and team H.E.A.T. around the planet battling new mutations and other supernatural beasts. The series not only had Godzilla battle several other kaiju, such as a Giant Bat, but also face a fleet of invaders known as "Leviathan Aliens" in a tribute to Destroy All Monsters, and an eccentric billionaire rival of Nick's. In an ironic twist from the original Godzilla TV adaptation, in the 1998 film, Godzilla has a flammable power breath similar to fire, while in the series, his son breathes a green atomic breath.
Godzilla 2000: Millennium: This film does not refer to the events of any film before or after it. All that is established is that Godzilla has been attacking Japan for some time prior to the film's events. Godzilla.jp's entry for Godzilla 2000: Millennium confirms that it is in fact a direct sequel to the original Godzilla, and that the Godzilla featured in the film is the second Godzilla in that continuity, after the original 1954 Godzilla.
Godzilla vs. Megaguirus: Although Godzilla in this film sports the same design as in Godzilla 2000: Millennium, the two films do not share continuity. Godzilla vs. Megaguirus shares partial continuity with the original Godzilla, as Godzilla still attacked and destroyed Tokyo in 1954. However, in this continuity the Oxygen Destroyer was never used and Godzilla simply swam out to sea, only to return and attack Tokai in 1966. Godzilla was not seen again until 1996, when he attacked a plasma reactor in Osaka.
Godzilla, Mothra and King Ghidorah: Giant Monsters All-Out Attack: Another standalone film, GMK is a direct sequel to the original Godzilla. In this continuity, Godzilla was killed by the Oxygen Destroyer in 1954, but the JSDF claimed credit for killing him in order to avoid facing ridicule and assure the citizens of Japan that they were safe. Eventually, Godzilla was brought back to life and possessed by the restless souls of those killed by the Japanese military in World War II, and returned in 2002 to destroy Japan. This film also makes a passing reference to the 1998 American film, as Taizo Tachibana mentions early on that a giant reptilian monster similar to Godzilla recently attacked New York City. A soldier asks if the creature was Godzilla, while another responds that the Americans think so, but the Japanese doubt it.
Godzilla: Final Wars: Despite its numerous nods to previous films and inclusion of stock footage, is an entirely standalone film that shares continuity with no other films. In this continuity, Godzilla first appeared in 1954, prompting the formation of the Earth Defense Force. In the following years, the EDF battled against the countless monsters appearing around the Earth. At an undisclosed point prior to the main events of the film, the Gotengo lured Godzilla to Antarctica and managed to trap him underneath the ice. For the next several decades, Godzilla remained imprisoned in Area G while humanity was kept safe from other monsters by the EDF. It is not disclosed in what year the main events of Final Wars take place, as supplementary materials only refer to it as the year 20XX, but it is presumed to be sometime in the near future.
Shin Godzilla: is a complete reboot to the franchise in which Godzilla attacks Japan for the first time in the modern day. After a disaster in the Tokyo Bay Aqua-Line, Deputy Chief Cabinet Secretary Rando Yaguchi proposes that the culprit is a giant creature, only for his suggestion to be laughed off. However, Yaguchi is proven right when a huge gilled creature swims up the Tama River and comes ashore in Ota Ward of Tokyo. The JSDF is unable to mobilize in time and the creature escapes after leaving a trail of destruction. Now, Yaguchi and a ragtag team of bureaucratic rebels band together to find a method of defeating the creature, dubbed Godzilla, as he continues to evolve and returns to menace Tokyo again.
Godzilla Anime Trilogy:GODZILLA: Planet of the Monsters, and that it would be the first entry in a trilogy of anime Godzilla films. GODZILLA: Planet of the Monsters was released to Japanese theaters in November 2017. The second entry was released in May 2018, followed by the third film was released in November 2018.
Godzilla Power Hour: The series followed the adventures of a team of scientists on the research vessel called the Calico which was headed by Captain Carl Majors. The rest of the crew included Dr. Quinn Darian, who is a female scientist, Brock Borden, who is her African-American assistant and Carl's first mate, and her teenage nephew Pete Darian. Also along for the ride was Godzooky, the nephew of Godzilla and Pete's best friend who had a light-hearted role in the show. He could fly using his small wings under his arms, though his Uncle Godzilla was unable to fly. Whenever he tried to breath fire, he just coughed up smoke rings and he never seemed to have the ability to shoot laser beams from his eyes. The group would often call upon Godzilla by using a special communicator known as the "Godzilla Signal" when they were in peril, such as attacks by other giant monsters. If the communicator was not present or lost, Godzooky would use a special "howl" to summon him. Godzilla's size in the animated series shifted radically, sometimes within a single episode or even one scene (for instance, Godzilla's claw will wrap around a large ship, and only minutes later the team of scientists fit rather neatly on Godzilla's palm). In addition, Godzilla's trademark atomic breath was altered so he breathed simple fire. He could also shoot laser beams from his eyes, much like Superman's heat vision.
Godzilland: Godzilla and the other monsters are portrayed as young children that live together as friends. They live on the island with Mothra, the only adult in the show, who acts a maternal figure to the other monsters while raising her two twin larvae. Godzilla frequently gets into arguments with his best friend Anguirus, which often drive the plot of the episodes. Mechagodzilla is portrayed as being very lonely and desperate to make friends. Because of this, Mechagodzilla tries to kidnap Godzilla's friends and force them to be his new friends, forcing Godzilla and the others to save them. Despite being seen as an antagonist, the mecha's lonely nature means that he often ends up being taken in by the others as a friend once those he captures are rescued.
Godzilla Island: In 2097, most of the world's monsters have been rounded up and are living on an island in the South Pacific dubbed Godzilla Island. The kaiju are kept content on their island home, and are monitored from the G-Guard base in the center of the island. There, Commander Besuke Jinguji watches and monitors the monsters day after day, with only the spherical robot Lucas by his side. However, the monotony of the job and of the monster's lives comes to an abrupt end when a gigantic UFO arrives on Earth. Inside is the Xilian Zagres, who, under the command of her leader, the Giant Dark Emperor, is hell bent on taking over the planet, starting with Godzilla Island. However, as her ship begins to attack the island, a smaller ship arrives and defends the island, the monsters, and the base. As the Commander and Lucas scratch their heads, perplexed by this new turn of events, a young woman suddenly appears in the base. She introduces herself as Torema, and says she has come to help defend the island from Zagres's onslought. However, the three heroes have a long road ahead of them, as the evil Xilians have an entire army of monsters at their disposal, and more than a few surprises to boot. It will be up to the Commander, his daughter Misato, Torema, Lucas, and the horde of monsters living on Godzilla Island to defend their home, and the world, from the coming invasion.
Godziban: Godziban episodes are divided into a number of unique segments, typically anywhere from two to four. The most prominent of these is Go! Go! Godzilla-kun (Go!Go!ゴジラくん Go Go Gojira-kun), in which Godzilla's son, Godzilla-kun, teaches his brothers Minilla and Little various Godzilla skills, such as breathing atomic breath or tail sliding. Attention! Godzilla (かまって！ゴジラ Kamatte Gojira) debuted in the show's second episode and follows Kamachi, who appears to comfort people in times of need.
Godzilla Singular Point: In the year 2030, Nigashio City, Chiba Prefecture. Yun Arikawa of the local "multipurpose" Otaki Factory investigates clues in a European-style house, long thought abandoned. Mei Kamino, a graduate student studying fantasy creatures, investigates mysterious signals received from the Old Tsuguno District administration bureau "Misakioku." Two strangers, visiting completely different places as part of completely different investigations, both hear the same song. This song brings the two together, and leads them into a battle beyond imagination which grips the whole world. A mystery left behind by a lone researcher, monsters appearing across the globe, and a world dyed red. Can these two face down the hopeless future (Godzilla) that threatens mankind...? Brought together by a mysterious song, a grad student and an engineer lead the fight against an unimaginable force that may spell doom for the world.
This verse is very powerful as it has several broken abilities and ranges widely in power, very often there are characters who are planetary threats, there are also casual planet, star and solar system busters. The God tier of the verse is King Ghidorah (Anime), who is a 4th dimensional being who's mere presence distorts space and time itself, who cannot be 'killed' on the 3-D level and will eventually devour the entire universe if not more as one of the strongest in-verse characters.
Crossover-wise, the universe reaches cosmic to multiversal levels of power, with Godzilla, Mothra, Kiryu and others being consistently on pair with Universe level beings, and evolving into stronger forms that puts them at the level of the Multiverse level Gods.
Godzilla himself has several impressive feats such as battling Thor and the God of Thunder comparing him to the World Serpent, to strongerplacing Godzilla at Solar System level, also reacting to and shooting a comet carrying Monster X/Kaiser Ghidorah while it was still in space, tanking an absolute zero blast, surviving as nothing but a beating heart, and moving the Earth's tectonic plates from the indirect force of Heisei Godzilla and Larva Battra's battle.
For a thread detailing the power of many beings in the verse, click in this Tier List.
Humanity and alien races had developed High level technology that includes spaceships to travel between the solar system, time machines, mental control machines, armament capable of hurting the kaiju such as the hyper maser cannons, chemical weapons that can destroy entire cities at molecular level like the Oxygen Destroyer and finally the definitive weapons known as Mechas to fight the Kaiju. The technology of alien races ranges from weapons able to hurt the kaiju to being able to destroy Large Planets such as Peaceland with ease.
Kaiju: Kaiju (怪獣 kaijū) is a Japanese word that literally means "strange beast" and is usually translated as "monster" in English. Traditionally, kaiju can refer any sort of strange creature, but in recent times the word has become associated with a genre of tokusatsu entertainment, specifically Japanese cinema that involved giant monsters. The most powerful kaiju are at times advertently referred to as daikaiju (大怪獣 daikaijū) the prefix dai- emphasizing great power or status and is usually translated as "giant monster."
Mecha: Mechas are typically depicted as humanoid mobile robots. The term was first used in Japanese (meka) after shortening the English loanword mekanikaru ('mechanical'), but the meaning in Japanese is more inclusive, and "robot" (robotto) or "giant robot" is the narrower term.
Keizer: A Kaiser, also spelled as Keizer, is an extremely rare type of mutant who is granted additional powers due to the fusion of M-base and human DNA. In addition to the standard mutant abilities of superhuman strength, heightened reflexes, superior coordination and increased agility, Kaisers are able to control any other life-form by telepathic means if that organism has M-base.
Shobijin: Are tiny twin priestesses of Mothra who first appeared in the 1961 film, Mothra. They have been featured in nearly all of the character's film appearances since, as well as in several comics and video games. While their names and portrayals have varied over the years, Mothra's Shobijin act as her link to humanity, interceding on her behalf with the rest of the world. The Shobijin can telepathically communicate with Mothra and translate her messages, and often sing in order to summon her or pray for her aid.
Mutants: are the genetic descendents of both humans and Xiliens. They were trained as a form of highly elite soldiers by the EDF under Commander Kumasaka. In Godzilla: Final Wars, all but Ozaki (and later Kazama) fell under the control of X. The most notable Mutant is Ozaki, who used his Keizer Energy to revive Godzilla.