All the hate, rage, and anger make him catch fire.
This is Terminus, my Kommo-o

He has a burning hatred for Lucario since he used to be one of the best fighters in Alola. Then out of nowhere, this Lucario comes, bringing a strange stone that amplified his power and appearance, and he was beaten easily, and it was humiliating.
No one in the fighting community was able to take him seriously after he lost, so he left with Solgaleo and Lunala to become a speaker at various places around the mainland that are holding seminars near those areas.

He really doesn't want to go back to Alola when he's done, but has little choice since Solgaleo assigned him as a retainer, but doesn't mind too much.

His tuxedo he wears is made up of a very flexible and durable material. There are holes under his arm scales that were specially tailored, and the suit itself is entirely fireproof. And it's the only think he'll wear, so he has a ton of them. Though his personality says otherwise, he tries to keep a formal look. The fighter in him burns strong as ever, which is why he made the tux very flexible, and the reason why it's fireproof, is because this guy can take his Fire Punch to a whole new level.

Terminus is by all means a good guy, though can get annoyed pretty easily. His retainer partner being always overly-excited tends to annoy him to no end, but he puts up with it.

He learned his Fire Punch move after he lost to the Lucario, and it tends to freak out Solgaleo sometimes. The power behind that move comes from his burning hatred and passion for proving to others that he can win. He lost his friends and respect in Alola, and someday vows to get it back. For now he's a retainer, and has been training as he travels.

Some people call him The Fiery Kommo-o

Art:  Blake.Zekky