User blog comment:DeathGodPrayer/Talk About What You Want!/@comment-98.77.248.141-20120530010852/@comment-68.234.125.79-20120603195757

It either wouldn't be allowed, or they'd have to make it a handicape match, since Issei wouldn't be on Rias's team.

Of course, Issei would either refuse to have the match, or disqualify himself.