Hi, aokshin.
I gave this idea for another person to do, and he said it would work for one combo, but it was you're design. So here is what I wrote to my friend.
I have an idea for a Greeed
There's one I thought of that's creates Yummies by using cell medals on animals instead of humans. By doing this, the Greeed wishes to see what kind of desires the animal truly desires. For example, it uses one on a lion to see why it's the king of beasts, and most of it's desires is to be free from it's cage. Another example is when he used a cell medal on a scorpion, and it wishes to become a better predator. Behavior wise, it's very proud and arrogant, and will do whatever it takes to get it's core medals back, even if it meant killing the other Greeeds.
The Yummies develop inside the host, enhancing the host's abilities for a short amount of time. When fully developed, the Yummy will come out of the host, and will act mostly on primal instincts. It can go back into the host if necessary. OOO either has to remove the Yummy, or just destroy it quickly before it escapes. The Yummies are more animal like than humanoid (think of the second Yummy, and a few of Mezuru's Yummies)
When I submitted my idea, he said it would work for the Wild Greeed. So now I come to you, wondering if you could grant this request.