Explosions which are AOE, it even grazed sans and GG, Teleportation counters Danmaku, Time Slow makes hitting him much easier. Waluigi takes this. Tagging Waluigi would be really hard with teleportation on his side plus time slowing. And AOE attacks, plus faster speeds with time hacks, and grazing sans would kill him. Tornadoes which would be a issue for Sans. And acrobatics making Waluigi harder to touch.