I played Super Smash Brawl with a fiend but she beats everyone with Sonic, how do I win?

She's been virtually undefeated by anyone but me. Unfortunately, although I'm the most humble and sweet-natured person I know, I'm hrrobly full of pride. I'm great at Seamus Zero Suit (but who isn't?), Pit, Ganondorf, and mostly anything that flies and is agile but won't move spasmodically or too quickly. Please help.