This can only be truly answered by Game Freak. It has been agreed upon by many people, however, that this is a way to make people buy Nintendo Switch Online. Realistically, who would want to be allies with Solrock, Wobbuffet, and Eevee? No one, because they're awful. Them being garbage is the whole point, so you have an incentive to buy NSO (competent players).
If you want a G-Max Corviknight, and don't want to raid, you can apply Max Soup to a regular Corviknight, provided you have the DLC.
Hope I helped!