Master-of-all-things-Smash Master0fHyrule highlights this unbeatable glitch (first discovered by by YouTuber StylesX2) for those playing Pac-Man in Super Smash Bros. for Wii U, and it's something Nintendo might want to get on before EVO 2015.
In short, if Pac-Man can lay down his trampoline and then jump and change forms at the proper moment, his opponent will fall right through the stage, an outcome that is fatal unless the opponent has some means of recovery, like Kirby or Jigglypuff.
No idea how long this has been in Super Smash Bros. on the Wii U or if it's a glitch introduced with the latest patch, but try it for yourself, it appears to be nearly foolproof.