I literally thought of making a suggestion about the 3rd option you mentioned that is, Changing Regular Pokemon into Mecha Forms. I think it's a really cool idea. Let's be honest, there's an abundance of Mounts and Huntable Forms in the game and new ones are added whenever an Event approaches. Adding New Forms which can be only obtained by PvE Coins is a different approach and can bring new interest in the game. Especially for players who are not interested in hunting.