[Sword & Shield] Noibat Galar Mine No. 2 “fire”?

Noibat battle in mine. Prior to approaching there appeared to be "fire" swirling around him. After capture I also got the message "Received 229 W". I had caught one previously but wanted to catch this one due to the fire swirling in the over world. Any idea the significance?

The yellow aura means you've encountered a Brilliant Pokémon! These have better IVs/stats than your average mon, and can also know an egg move that they'd normally only be able to get by breeding. They also give you watts as you've experienced, the currency to purchase things in the Wild Area.