So there isn't much to say about this idea because it depends on the author how he writes it.
So obviously the MC will be super OP with Beerus' powers in the world of Highschool DxD
So if you have a good sense of humor and you are a good writer please use this idea!
You can make it a harem if you want.
Just make the MC be like super funny, while annoying the main characters.
Kind of like One Punch Man but in the world od HS DxD