They don't have to be SUPER obscure. Just exclude the founding members of these teams:
Peter David's X-Factor
Also exclude Havoc and Polaris, and Gambit and Rogue.
You get the idea.
But I'm glad that people are responding to this one. I kind of miss the old Excalibur crew (Aside from Kurt, Rachel and Kitty.). Also, Pete Wisdom. Has he been seen since Secret Wars? Also, Exodus, The Living Monolith, Scalphunter, Selene and a few more.