I do believe LuxrayBlast asked which Pokemon I think best suits Sin, and my conclusion has come down
to these two pokemon: Weavile and Drifloon.

Weavile. This pokemon's stats and fighting style are pretty close. Crappy defense and Hp, crazy Attack and speed, can use SpAt that's not very strong at all.
I also think that weavile would make for an excellent sparring partner with him. He'd have a lot of fun. A pokemon he can enjoy their company.

Drifloon. I dunno. Maybe you can imagine why, but if you can't you should read some of Drifloon's pokedex entries.

His starter would be Litten (Named Flamedikat), He'd have a Shiinotic, and Ribombee.