Stalwart and Propeller Tail are copium abilities they really want to make work. Like redirection immunity is cool but you give up your item slot or pass-up on much better abilities in the case of Skewda and Arch. They buffed Storm Drain/Lightning Rod to do something in Singles, but Stalwart somehow not just being Mold Breaker is ???
I think the examples of ITS SO OVER were Drampa/Crab/Chandy (Levitate is actually good on Mega Chime in a Singles context so I'll ignore it here) primarily. The only Megas prior to them and Dragonite that kept old abilities were Scizor, Ttar, Aboma, and Blaziken. In the case of all the latter though, the abilities they kept are insanely powerful on their own, Scizor doesn't care if technically Bullet Punch with a Band or Life Orb is stronger than Mega Scizor, the stat upgrade is just that worth it. Of all things, Crab is the only one that could say the same to any extent, you actually can take a hit now and you're slower which is better for Trick Room.
Drampa largely is just More Of The Same, but it's a mon that peaked in viability in Gen 8. It being slightly more able to take a hit is nice, but Goltres made Berserk work the way base Drampa couldn't for a reason, and Mega Drampa doesn't change much.
Chandy well, I have no idea other than it wanted to be a special snowflake from the other Fire Megas.
I wonder if not for balancing reasons, why these in particular didn't change at all. Some of them are at least very flavorful and useful, so why Infiltrator Mega Chandy?
