What if Bandai Namco Studios devs had replaced Pikachu Libre with an untrainable evil mass murderous wild Arbok for a playable fighter Pokémon in Pokkén Tournament and DX?
I doubt they would, as Pikachu is the game's mascot and "branding" and "popularity" and everything, but that is an interesting idea.
Most of the fighters are bipedal, the only quadruped is Suicune I believe, so I kind of doubt Arbok getting into the game.