Mightyena has some great abilities in Intimidate and Moxie. Snarl is a useful move in doubles. But other than that he's got nothing going for him, lackluster move pool, bad stats. He's just an objectively worse Incineroar, hell he's a worse Alolan-Raticate.

Castform should theoretically be an easy choice for ALL types of weather teams, but with base 70 stats across the board and a bit of move synergy but not a lot, it's just not worth it. Bump all it's stats to 100, buff it's ability with some perk that's unique to the different weathers. Give these boys something, anything!