Rogue

Anna Marie's mutant power manifested in a way that prevented her from being able to touch another person without absorbing their essence, personality, and in some cases, their powers.

Out of fear of hurting her loved ones, she ran away (hence the nickname, "Rogue") and eventually joined up with the Brotherhood of Evil Mutants. Acting on their orders, Rogue attacked Carol Danvers and permanently absorbed her powers of tough skin, superhuman strength, and flight and used those powers to attack the Avengers and X-Men.

Being unable to control the mental personality of Carol, Rogue fled from the Brotherhood to the X-Men and joined them, where she has been fighting for the peaceful coexistence of mutants and humans most of her life.

These days, Rogue is fully in control of her powers.

2D Fighters
Rogue defeated Chizuru Kagura in the opening round, Ai in the second, and Clark Still in the third, before being defeated by Zangief.

Children of the Atom
Rogue defeated Psylocke in the opening round, but tied with Wolverine in round 2, eliminating them both from the tournament.

Goin' Green
Rogue eliminated Master Chief in the first round, but lost to Ms Green in the second round.