Gigantamax should be allowed instead, as Dynamax could be comparable to any Pokemon being able to Mega, just not changing form.
1. A Gigantamax Pokemon would be completely predictable just from team preview, as well as the team accompanying it.
2. A large majority of them are inferior to their Dynamax counterparts, and none of them are top tier competitive threats either.
3. Only Charizard (Blaze locked btw), Butterfree, Gengar, Lapras, Drednaw, Coalossal, Toxtricity, Hatterene, and Grimmsnarl can set up weather/terrain or boost their own offensive stats with a STAB Max move, out of 400 Pokemon.
https://pastebin.com/SUSdSRri 