I will leave a couple of ideas that could be good, for now what they have done is very good
-Be able to choose if you are passive or dominant with the mon
-Add more ingredients to create curious effects (I don't have any in mind at the moment)
-The strange altar to the right of the stage catches my attention, maybe add something there later?
-More mons (Salazzle, houndoom, mightyena, Gardevoir, Serperior, Grovyle, etc, etc)
At the moment that's all I have in mind for ideas, I like the result they have created so far