Grigori would kick Billy's mullet having ass without breaking a sweat.

It depends, normal billy, grigory wins. Flayed billy, billy wins.

Billy cheated to win against Steve.

Grigori has training, Billy doesn't.

There are no rules when fighting so the 2 can cheat all they want. Grigori would win thou

Who cares about rules? The fact is Billy has never been shown winning a fair fight.

I add homelander to the fight

Don't care about winning a fight fair. You win the fight however you can and Russian dude would win anyway with or without Billy cheating