We know for a fact people consume tropius bananas, and cherubi, wishiwashi, basculin, and crabrawler (or at least its claws) are described as tasty, so it's implied people have eaten them at some point. Farfetched is described as delicious in one of the earlier dexes. The blissey line produces edible eggs. That's all that comes to mind. Like
>>32658084 said, you can probably eat any mon if you're hungry enough, but I just wanted to list the ones we know for a fact are consumed in some fashion.
