You know, given his backstory and personality, I can see Giles as a Hogwarts expellee. Probably thrown out and had his wand broken around fifth or sixth year for practicing the Dark Arts, which is why he can't really do anything useful beyond rituals unless he really puts his mind to it.
OBJECTION!
Fishing is the one recreational activity Sousuke actually does understand.
The SR Team and SG-1 would still make a great teamup, though, especially when SG-1 needs some heavy fire support.