Steela was cursed by Evil Mew while walking around. Which is why her colors are different.

She also was given a master ball, this was a special master ball though. If a Pokémon looked at it they were put under her mind control indefinitely.

However the master ball can only control 15 people at a time, which is the downside.

She also knows a new move called laser ball where her master ball shoots a laser that destroys everything it touches.

Steela is really wicked and totally tubular.