I always thought Teela should stay older than Adam because she was always talking down to him anyway. Works better in my head anyway.
People keep mentioning Captain Randor or MYP Randor, but it was Battle Armor Randor and Marlena that would be the awesome set--and he must come with an alt head wearing that crazy helmet!
Callix is taking some knocks here for being the redshirt, but I always thought his full story was untold and that there may have been a reason Hordak singled him out to die (other than that he hated bad news). Perhaps he was a spy for the Rock People or something. That said, always thought he'd make a great opponent for Snake Face.