Empoleon as a pokemon sucks.
Galarian Moltres is a giant bag of wasted potential, especially its signature move.
Galarian Articuno's signature move is fucking stupid and I hate it.
Galarian Zapdos is probably the best out of the three as a pokemon and even then I don't like it as much as I could have. What else do I say here?
These 5 mega evolutions suck the most as a pokemon:
Mega Abomasnow - Shitty stat spread + shitty defensive typing + unhelpful ability, what else is there to say? (again, you didn't have much viable options for good stat spreads since base Abomasnow's stat spread is horse shit)
Mega Absol - Not fast enough for how frail it is, just gets completely obliterated by priority. Very poor abuser of Magic Bounce, even Mega Diancie of all things has better bulk than it.
Mega Ampharos - Not bulky enough for how slow it is. Mold Breaker every once in a while will save you / win you the game but even then you could've used a better Mold Breaker pokemon and got the same, if not better, results as you would with Mega Ampharos
Mega Banette - read my rant on Mega Banette and you should see why this sucks.
Mega Camerupt - I'm ok with it being as slow as it is but it should've had way better bulk to justify it. Also just an extremely poor abuser of Sheer Force due to how slow it is.
Playing with stall is super boring and even with a wincon/finisher on your team, you're generally better off playing faster playstyles.