Porygon2 will be my choice in Crystal :D
I'll probably update this every once in a while :|
Beat Rival with Lv 8 Cyndaquil, sharked wild Porygon2, got it at Lv2. Beat Falkner easily, went to union cave and taught him Swift. Beat Bugsy and Whitney, and now going to Ecruteak. Currently Lv 30.