>>38864843I imagine the moveset any dynamax'd mon gets is pre-determined rather than a bunch of new dynamax moves based on the mon's normal moveset. So, imagine ir being based on the mon's type, and only having "strong Grass attack physical" and "strong Grass attack special" for Grookey, for example. Would make it way more balanced, and arguably weak.
Plus, they might make all gimmicks (Megas, z-moves, and Dynamax) listed in the same value, so you couldn't, say, dynamax a mega Pokémon and have another mon on your team use a Z-move.