All this talk about Final Fantasy characters makes me think that we should come up with some Supers for various FF characters. You can use any characters, even creatures from the games if you want. It doesn't matter how likely or impossible their chances of being in this game are.
Vivi (FFIX) Level 1; Steiner Steiner appears with a flame-enchanted sword and slashes in the area in front of Vivi, killing a single opponent
Level 2; Trance Vivi temporarily enters his Trance state. All of his normal spell attacks become double casted so they're bigger scale and become capable of killing
Level 3; Meteor A cutscene shows the meteor in space forming and coming speeding towards Earth. A timer appears on-screen showing how long it will take for the meteor to reach Earth (10 seconds). The match continues until the timer reaches 0 and then the whole screen goes red to show that the meteor has arrived, instantly killing everyone on-screen.
Lady Lilith (FFXI) Level 1; Durance Whip A load of black thorned vines form around her body and then lash out in front of her from her hand, killing a single opponent.
Level 2; Moonlight Veil Lilith creates a minature moon above her head, which then cracks and shatters, releasing a shockwave outward that kills opponents around it.
Level 3; Dark Sun A cutscene is shown of Lilith transforming into her ascended Goddess form and creating a minature Dark Sun. This minature Dark Sun stays in the center of the stage for 10 seconds, and pulls everything towards it. You can resist it's gravitational pull if you stay on the ground and move away. Anything that touches it dies and if it manages to pull in and kill at least 5 enemies before those 10 seconds are up, then instead of just dispersing in the end it will explode and kills all enemies that are near enough to it. You have to be careful though because the explosion effect can kill Lilith too.