Prince of the Cosmos
If he rolls up anything, it's likely stuff he tore apart himself. Dogs are jerks sometimes.
Maybe the Mario costume isn't your thing and you prefer animals to stay animals. Why not try Yoshi? Your dog always wanted to be a dinosaur; that's why he keeps chewing your shoes.
Everyone gets so caught up in Mario and Luigi and Peach and Bowser, no one stops to remember the little guys like Paratroopa. Perhaps you can remedy that with a snazzy costume.
Spider-Dog, Spider-Dog, does whatever a Spider-Dog does...we know that's not the song, but Spidey does make a great costume.
If Steve Rogers himself owned a dog, we have no doubt it would look like this guy here. He even has his own shield, perfect for deflecting attacks or a plate for treats when turned upside down.
We love the idea of doggy Wolverine, but for authenticity's sake we'd have to leave his nails untrimmed for a while, and that would only end up badly.
I AM THORGI, CANINE COMPANION OF ODIN. FEEL THE WRATH OF MY CHEWY SQUEAKY HAMMER!
This is a no-brainer: Amaterasu is a wolf god, dogs are basically domesticated wolves, voila! Instant God of the Sun.
We LOVE the idea of Dogvahkiin, but we assume Shouts would turn into Barks. It's hard to speak an ancient dragon language when one can't speak at all.
"That dog stole food from my bowl and sniffed my rear end without my consent...VENGEANCE SHALL BE MINE! I AM THE DOG OF WAR!" Don't mess with Doggy Kratos.