The megas don't have dex entries, so we cannot see their base stats ingame. This is not too much of a pressing concern for pc, since in pc the PRO window can be minimized and other windows can be seen. But for mobile devices when we go out of the PRO app we are logged out automatically, so there is no way to check the base stats whilst in a battle, which is helpful sometimes to mainly check if enemy can be outsped.
You don't need to add the whole dex entries and sprites for megas since that will be too toilsome, for now you can just add the base stats of mega beside the normal base stats in parenthesis in a different color, like Atk: 80(100). This can be in my opinion a nice help.
Also on the same note, the alolan forms already have dex entries but they are only accessible from the spawn list by clicking on them, if this can be fixed and their entries can be accessed normally, it will be a great leap for pokedex. Thank you.