After browsing and participating in the vs battles threads for some time, I have come to realize that a lot of people tend to gloss over or forget certain very relevant aspects of the 'Standard Battle Assumptions ' which are in effect by default in any thread unless individual changes to those assumptions are otherwise specified. These little pieces can have very relevant and dramatic implications on the outcome of a battle, so I will be going over the ones that I feel are forgotten too often.
1) State of mind: In character, but willing to kill. The characters will employ their usual battle strategies, including flaws such as being casual, however, must be willing to kill the opponent even if they usually won't.
As a whole, this rule isn't forgotten much.. however the first part ('In character, but willing to kill.') is commonly the only part that people remember or bring up. The second part is also very important though, as it directly contradicts the considerations that many people use to decide who to vote for. It's super common for someone to argue that one fighter happens to have one or two very specific and rarely used abilities that are capable of defeating the other fighter handily, therefor they win the match. While it does make sense that the existance of such abilities certainly creates a victory condition for that fighter, the problem here is the assumption that they would start the fight off with immediately using those rarely used abilities instead of going for their 'usual battle strategies, including flaws such as being casual', strategies which will most likely be very innefficient compared to their optimal strategy - and in fact they may lose before ever getting a chance to try that optimal strategy... making its existance a moot point.
Now, you could try to argue that any fighter who isn't a moron would always use their best, most optimal strategy against each opponent but then you are forgetting two other frequently forgotten standard battle assumptions:
2) Knowledge of the other character/verse: The fighters will have absolutely no prior knowledge of each other.
3) Preparation time: None.
Fighters are not given any time before the match to sit down and consider what would be their best strategy to use against their opponent for that match, and even if they were it doesn't help much since they start off the fight with 'absolutely no prior knowledge of each other' including knowledge of the other verse. In other words, standard battle assumptions specify that both fighters are going in blind, the only chance they have to learn about their opponents abilities and stats comes from the actual fight itself.
These three pieces of the standard battle assumptions come together to create a situation that forces both fighters to actually engage in a battle where they learn about each others abilities and eventually one comes out on top likely long before either character has shown everything they can do and probably before either character actually manages to consider let alone implement their most effective strategy or attack. Assuming one character doesn't blitz and oneshot of course, which is part of the reason those kinds of stomps are not permitted.
It is my own opinion that these three pieces of the standard battle assumptions are the cornerstone of interesting vs threads. The outcome of a fight is more up for debate when you cannot determine the winner by glancing at the profiles for a few seconds, you have to consider the actual personality and fighting styles of the characters and figure out what they would really do if encountering their opponent for the first time, how they would escalate the battle and adapt to abilities and techniques they haven't seen before, who would come out ahead in the very first exchange of combat where they don't know anything about each other yet, etc. Even if one fighter has an edge in stats and ability interactions on paper, their personality or fighting style or intellegence might not allow them to exploit those advantages enough to win.
That debate right there is what we have vs battles for, not so we can say 'character A instantly uses the optimal strategy they could use against character B assuming perfect knowledge with 100% perfect execution' and then chalk up a win on someones page. The fun part is 'what would the fight look like while they got a feel for each others strengths and weaknesses and who would be the first one to both discover and apply an effective strategy?'.
So the next time you roll up into a vs thread, ask yourself if the arguments people are presenting for why one character would win actually make sense given that unless otherwise specified, the fighters will start off with no prep time or knowledge of the other and will be fighting using their usual tactics.
Bonus Round:
4) Time: The time and date are chosen in such a fashion that all characters are at their strongest. Paradoxes like it being night for one character, while being day for another are acceptable here. If extreme advantages are generated via this regulation to one side, a balanced alternative should be discussed in the thread.
Even though I'm personally not a fan of 'great ape gg' arguements, the fact remains that according to standard assumptions the time and date of the battle is optimal for both characters, meaning the fight will always for example start on the night of a full moon for dbz characters that want to use their gorilla mode.
Edit: As DontTalk mentions below, this 'great ape' example is sort of pointless since fighters must start and stay in one transformation/mode for a fight and so can't be suddenly powering up with something like kaoken or great ape mode anyway, however I leave the example in because it illustrates the idea of the time rule in a way most people would be able to relate to.