Easily King of All Cosmos...the guy is omnipotent, he's sneezed solar systems out of existence by accident

And then you run the gambit of Disgaea Overlords including Laharl (and most other high level demons in Disgaea for that matter), GoW Kratos, GoC Lenneth, Testaments, Giygas, Blues Eyes KOS-MOS, T-elos, Wilhelm, True Beast Rune Luca Blight, Fully Stocked Ratchet, Cutscene Dante and Vergil, Reaction Command Sora, Hyper Sonic, Mewtwo, Endgame Prince of Persia, Dracula, FF Aeons, Perfect Materia FFVII characters, anyone of a multitude of insanely powerful game mechs, top tier demons in Darkstalkers, Destruction Fayt, Alteration Maria, a ton of RPG final bosses or secret bosses, Max potential Zero, Fully equipped Samus, KOTOR Jedi, JC Denton, Alma, Infested Kerrigan, Amaterasu...

They could all qualify to a certain degree, though some are obviously better than others.

They have tons of data for SSBM...including framerate, DI, speeds, priorities, length of wavedash, hitboxes, teching, shffling, and more...the tourney scene is very fiecre and its the biggest fighter scene right now. Its the only console game other than Halo 2 that is sponsered by MLG (that I know of >_>).  Its easy to pickup, play and have fun (though button mashing will get you killed even in casual matches) but it also has a great tournament circuit...

And the changing tier list only reflects the changing metagame as new skills are discovered and old strategies are rendered obsolete.