Had this in my previous sketchpad. Honestly I grew tired of giving Byakko a modern attire so I just gave him a traditional japanese garb. Basically a sleeveless Haori with a sash, a fundoshi, leg warmers, and arm bands. Still allows for full movement and probably made of very durable material to accommodate his energy absorption and growth.

Lets be real. He's just a large kitty just looking to get food and attention. I see no villain here. XD