I think both Sudowoodo and Delta Glalie should maintain Rock Head after Mega Evolving and Delta Sableye should have Vaporization. Dry Skin doesn’t suit a Fire type but it still benefits from immunity to Water. Why should Mega Magcargo be the only one with Vaporization?
Also since NPC characters rarely switch Pokemon, Mega Delta Mawile’s Arena Trap is basically useless in the game. I think it should have either kept Regenerator or gotten a different Ability.
Mega Delta Camerupt can just use Toxic so it doesn’t need Venomous. Granted, in this case, I’m not sure what you’d replace it with though. Maybe Liquid Ooze but that’s a very situational Ability and in order for Delta Camerupt to use it, you just need to get it’s regular form’s Hidden Ability and not Mega Evolve. Also, why not make it a Dark type when it Mega Evolves for the Psychic immunity?