User blog comment:B214/Talk About What You Want! 2/@comment-4547267-20141025044239/@comment-1359322-20141025171816

Even though Issei's body is that of Great Red's flesh with Ophis' power, it doesn't mean he has Great Red and Ophis' power. If he does, Issei wouldn't have been subjugated to the Evil Piece due to Ophis' power. Well of course i wouldn't doubt on Issei's new body having some powers, but i think it'll differ from that of Great Red and Ophis and will never reach the level of those two.