Overall, Therian Forme Thundurus is different from Incarnate Forme Thundurus by having a higher attack power and only slightly less defense. The defensive stat differences are minor, but the attack boost the Therian Forme has makes it a better Pokémon. When picking between these two, we recommend the Therian Forme.

Which form of Tornadus is better?

Tornadus' Incarnate and Therian Forms have access to the same moves, but players may want to opt into different movesets on this new available form. Air Slash is the best choice for Tornadus' Fast Attack because Bite is more centered toward doing chip damage.

Is Thundurus therian form good?

Overall, Therian Forme Thundurus is a great choice. We recommend you heavily consider your team before using it with your other Pokémon. The Pokémon's higher attack stats are beneficial, and it has a decent moveset.