The Mutant Funghi's are a group of 24 extra funghi which are unlocked after completing the original library of 30 in the original game.

The Mutant funghi instead of being added with higher equipment grades are found at random equipment grades.

The equipment grade is based on the lowest grade of device so if you simply change one of the devices (the warmer is probably best since it doesn't effect chances at rare funghi or growth rate) you can adjust it as you wish.

There is a list of confirmed levels where the Mutant funghi have been found below.

THEORY: I have a theory, which i'm testing out that all of the Mutant Funghi are available to grow at equipment level 10 but that each Funghi has their own "best" level to be most easily grown at.

Equipment Grade Mutant Funghi
1 Yeti
2 Strawberry
3 Choco, Squiddy, Anemony, Sumo, Yeti, Strawberry
4 Tasty, Rainbow
5 Peely, Pengy, Weedy
6 Sea Funghi, Archangel, Yeti
7 Boxy, Flammy, Funny
8 Weedy, Rainbow, Robo
9 Hissy, Strawberry, Basket, Venus, Rainbow, Spacy
10 Yeti, Tasty, Boxy, Hissy, Camo, Mushryoshka, Strawberry, Choco, Peely,Flammy,Funny,Basket, Squiddy, Anemony, Weedy, Venus, Rainbow, Master