>>412489821) Almost every single Mega Pokémon is either "this Pokémon is now a sweeper" or "this Pokémon is now a wall".
2) Some of the Mega Evolutions should have been ordinary Evolutions (albeit a bit weaker than their current iterations). e.g.: Pinsir, Mawile, Sableye, Banette.
3) You effectively can't fuck up when using Mega Evolution. Your Pokémon gets a 100 point boost to their base stats that they will keep until they faint.
Of the 48 Mega Evolutions, only 9 have any of their stats lowered. Of those 9, only 4 (Mega Mewtwo Y, Mega Heracross, Mega Garchomp and Mega Diancie) of three have important stats reduced. The rest have useless stats weakened in order to pump more into other stats.
The only way to actually fuck up a Mega Evolution is to Mega Evolve when the opponent has a Pokémon out that already counters you. Any wise player would simply just switch out.
Compare this to Z-Moves. Z-Moves are a one-time nuke to hit the opponent with. However, you can fuck up a Z-Move in numerous ways:
>opponent switches into a Pokémon that is immune to the move>opponent switches into a Pokémon that resists the move>opponent uses Protect, reducing the damage by 75%>opponent uses Substitute, absorbing the hit completelyDynamax only lasts for 3 turns after activating, meaning that it is possible to hold out against it and that it can at best sweep half of a team.
I've not played SwSh, but I would expect that Dynamaxxing either:
a) Forces you to stay in
b) Is ended upon switching out
Either way, this would have notable consequences, especially when compared to Mega Evolving, where if your opponent brings out a counter, you just switch out with no downside whatsoever.