I would be more willing to consider Dynamax broken if at least one of the following applied to it:
- Lasted more than 3 turns
- Modified other base stats besides HP upon Dynamaxing
- Wasn't available to literally any Pokemon at any time during a match
Keep in mind, you also have access to things like Toxapex, Galarian Corsola, Aegislash, Ferrothorn, Eiscue, Mimikyu, Unaware users, Focus Sash, Trick Room, and your own ability to Dynamax, all of which can be helpful when facing various opposing Dynamaxed Pokemon (hell, you could even use this
). It's also worth noting that Dynamaxing is arguably much less brainless than some other mechanics we've seen; you only get three turns to do anything with it, and if your Pokemon gets KOed or switched out, or if your opponent is able to survive all three turns, then you've basically wasted it.
I touched on this in a post
I made about a week ago, but I might as well reiterate that I still think it's too early to ban Dynamaxing; I had been lurking on Smogon for about 7 years before I finally decided to join back in 2016, and I remember seeing post after post complaining about Weather (and Dream World Abilities in general) in Gen 5, Megas in Gen 6, and Z-Moves in Gen 7 when those respective generations were new. But once people learned how to play the game with these new mechanics, we didn't see as many people screaming for them to be banned. Give the metagame time to adapt to Dynamaxing, and you might find that it's not so bad after all (or that there are a few bad apples you can weed out while still keeping the mechanic itself).
Also, spare me the bullshit excuse that "only bad players use it" (looking at a certain previous poster here). A pro adapts to the new game and utilizes the resources they have available to them in order to win; faux-pros and scrubs are the ones who blame exterior elements besides themselves for their own inability/refusal to adapt.