Pokemon Quest allows you to create new pokemon yourself. You just have to put the ingredients into the pot, and you will get a new pokemon after a few expeditions. The process can be quickened by spending PM Tickets.
If you don't want to experiment with creating pokemon, just press the button highlighted above, and the game will insert the ingredients automatically - you'll be able to just watch the results.
The pot also can level up - from bronze to silver. The better the pot, the more ingredients it can take, which allows you to create better pokemon.
As concerns the basic recipes, you can only decide about the color of the pokemon; the more ingredients you use of one and the same type, the better the chances of getting the particular type of a pokemon. For example: if you use four red mushrooms, you can be sure to get a fire pokemon.