I would like Raiden to win cuz I really want him to clap his Valkyrie's cheeks into the stratosphere. Hopefully the Hentai lords will make this possible.
I really don't see a path forward for Shiva in the rest of the plot unless everyone only gets one fight.
Shiva will do some burning move an then Raiden will use his other 3 forbidden techniques.
Then, I bet that, they will be so similar that it ends in an unheard of double kill and everyone freaks out.