you'll find the order of episodes here. If I say season 2, then go to season two. I've loaded them by name so...well, sorry but at least part one and two are named. Not all of season 1 are here. Some of them don't load properly.
I don't have the full season 3 either. 1st last episodes. If someone else has them, plz, share.
for missing episodes of x-men, try www.guba.com. they have a few good avi quality cartoons.