I know you didnt ask for it, but here are some Pokemon with the effects they could have.
Chandelure or riot We need dem Fire Blasts.
Talonflame (Brave Bird Id guess)
Braixen to satisfy the furries
Kekleon (spawns a swarm of other Kecleons to beat a random figher to a pulp, except for its "trainer")
Shaymin (would heal damage. Has a rare chance of spawning with a Gracidea, which would cause it to change forms and attack the player in the lead with Air Slash or something like that)
Wigglytuff (stands by doing nothing but smiling until he gets hit. If thats the case, Wigglytuff gets super angry and crouches a bit, causing the poor soul that attacked it to be blasted off by a spontaneous explosion regardless of their position on the stage. Disappears after 15 seconds or after attacking)
Palkia (something something visual effects, kinda like he did on Spear Pillar?, or maybe Spacial Rend)
Primal Dialga (freezes virtually anything but himself, including the timer, stage hazards, other players/items etc, then fires a massive Roar of Time that covers a wide part of the screen and can pretty much oneshot anyone in its path, including the player that summoned it)
Vaporeon (fires Scald in a small range in front of it. Players that get hit take a bit of damage from the attack itself, then 20% from the burn effect (overtime). The burn also slightly weakens attack power by a 0.7 multiplier.
Geodude (moves around the stage with tiny hops slowly. Punches if players get closeby with lackluster power, but can be picked up and thrown for massive damage)
Golbat (uses Supersonic (think of Mother Brains Onion Rings in Super Metroid) or Confuse Ray (slow moving projectile with infinite range) that confuses whoever is hit by it. Confused players have their button layout swapped around (the keys remain the same, just different mapping), and they also have a small chance of attacking themselves for 10% and no KB if an attack button is pressed)
Alakazam (can whack players with a spoon or use Psychic to fling them in a random direction. Obviously a strong attack)