First things first: Doubt it's intentional but the Corrosion ability on Glimmora seems to still have the buff it was given when it was Mega Victreebel's ability both in writing and in gameplay. I think it's a neat buff that should legitimately get added to base game but since we're supposed to be sticking to existing stuff it feels like an oversight.
On that topic, it's time for another long obnoxious wall of ability talk/prediction/suggestions post, thoughts on existing abilities + mostly Megas I'd like to see get their abilities revisited for one reason or another:
Clefable-Mega: Unaware - In champions this thing is 100% getting either a custom or a base ability with no in-between and we don't have customs anymore so. The flexibility to become unaware on a magic guard set is at least worth considering i
Dragonite-Mega: No change here but this thing is totally going to be the first fully evolved mon with friend guard and be unusable in singles so enjoy special moxie while you can. Otherwise I like
Sheer Force.
Absol-Mega-Z: Super Luck - lets you do some silly stuff with Focus energy > Sword's dance and caps it's power a bit compared to multiple swords dances alongside technician while still breaking just in a more unique way.
Chimecho-Mega: Punk Rock - Obviously it'd be renamed in-game. Levitate is fine too but they leaned into the sound stuff a lot.
Staraptor-Mega: Wind Rider - 5th tough claws mon and 3rd flying mega with it. Also another Fighting/Flying with this spread after gapdos and lucha. Rider instead gives it a few little options to come in and then a boost to either stay in with or use for extra damage pivoting after setting tailwind to it's team. Either way, more interesting and unique niche.
Froslass-Mega: Technician - Been suggested before but boosted frost breath/ominous/icy wind and chilling water suits it's dex entries very well and is a really interesting niche compared to the snow it doesn't actually use too well + we actually have all the snow setters besides ninetales including Mega Abomasnow in this format already compared to sun/rain with none so it's even less useful.
Garchomp-Mega-Z: Levitate - It's totally getting this. Doubt it's balanced but hey it's less crazy than it was on Delphox-Mega and that was fine.
Lucario-Mega-Z: Obviously this thing is getting mega launcher but it'd be hella banned with that so thank you for not doing that.
Scrafty-Mega: Lots of cool directions for this one which is exactly why I'm expecting magic bounce part 4
Kalos starter trio: Filter / Dazzling / Infiltrator - I presume we're not worried about these three being broken powercreep now they've been powercrept themselves in the DLC and the format power level is unironically high enough to keep up with Ape, Mag AND Sect.
Barbaracle-Mega: Dazzling - Really fits with the dex entry. Potentially ridiculous nonsense with shell smash which is exactly why i think game freak will randomly do it.
Hawlucha-Mega: Stamina just fits too well.
Golisopod-Mega: Stakeout - Regen good but this thing has legitimately 0 justification for it compared to the MANY other things we gave Regenerator like Alge.
Drampa-Mega / Tatsugiri-Mega: Drizzle - Drampa basically just being worse Tatsu now feels bad. Either or can swap. Same kinda goes for
Falinks-Mega: Rattled - Suits the little guys and is a nice punish to clicking knock and u-turn. We've never had an actually relevant Rattled user. Especially not one with an omniboost.
Glimmora-Mega: Merciless - I've personally discussed it before but with corrosion/debris pre-mega and the JP starfish pun, Glim is like the only shot we have of this getting distributed.
Baxcalibur-Mega: Skill Link - Yeah uh idk how else you fix this guy