>TQ
What a fun question! I was just thinking about this the other day when a few of us were talking about his Pokemon.

Assuming I'm the MC, Skwovet would feel familiar, your mom has one and there's a plush of one in the MC's room so I think it would be a Pokemon that I'd feel comfortable with. It's also the first one of his Pokemon that you ever fight, the only one that he brings evolved to fight a Titan, and he trades you one later, so it's kind of a meaningful Pokemon. A guy that likes to cook and a Pokemon that loves to eat seems like a good match up. I don't have any serious headcanons for most of his team, but since you team up with each of them to fight the Titans, I think they'd all be very friendly. Scovillain is probably hotheaded with a quick temper, Toedscruel is a bit silly and Garganacl is a gentle giant. Idk how his Cloyster would be, maybe a bit shy.

I would love to spoil Mabosstiff a lot, sneaking him extra treats from wherever Arven might have them in his dorm or giving him whatever he wants. Poor old pup deserves it after everything he did to protect Arven. I know that he would always love Arven best, but I can't blame him for that at all. I would just want to love and take care of him since Arven loves him so much.

I'd battle with him if he wants and help him learn how to get stronger or for fun, but I think we would more often just enjoy the company of our Pokemon in our daily lives.