If All Gimmicks (Z-Moves, Mega Evolution, Dynamax) became usable in today’s VGC (Gen 9) which one would you choose to use?

As the title says I had a thought about this the other day. If all gimmicks were to become available in gen 9, which one would be the best one or meta?

You can only choose one gimmick to use in a match and they follow the same rules from their own respective generation.