Any of that could be acceptable. Just depends on the quality of the sheet. A lot of story elements will come from the comics, so Ironman has traveled space with the GotG, and a version of Capt. Universe could presumably still have been a member of the Guardians at an earlier period in the group's history. I specifically left Venom off the Guardians roster in case somebody wanted to use Agent Venom or Space Knight Venom. Another symbiote could still work. Spiderman is a harder sell since you'd have to have the right voice and handle on the character, again it all just depends on the quality of the sheet and the iteration of the character presented. 

~KL~