Name: Bahamut
Game(s): FF1, FF3, FF4, FF5, FF6, FF7, FF8, FF9, FFX, FFT
Current Victories Over: Odin
FFnut's Notes: See, he'd be in all of them if it weren't for the original FF2...
Name: Shiva
Game(s): FF3, FF4, FF5, FF6, FF7, FF8, FF9, FFX, FFT
Current Victories Over: Ifrit
FFnut's Notes: Ice goddess... well, she's short one game from Bahamut, but then again, Bahamut wasn't a summon in FF1.
I'm going with B-man here. There's something about the gigantic dragon god of the summons that people tend to like.