Forming roller derby team?

Yes you will want quad skates. Blades are quicker, but quads are more stable which is extremely important when you get hit. If you actually do one day want to play against other people and form an actual league, NO leagues play with roller blades so you should learn how to skate on quads now. Plus, rollerblades boots go up high and for skating around a tight track you'll want a low cut speed boot such as that found in a quad skate.