Dreamup art series:
Dragons is mostly done,some characters won't be used like birdo.
Fish a lot are done,but are too much based on the character itself or too fishy.
Insects are started to do ,some are quite good others are unrecognizeable as mario bros characters.
Worms will be done soon
Butterflies soon
Sheeps?
Reptiles will be done after dinos or when the dragons are finished.
Squirrels?
Kangaroos I don't know the meaning concerning mario bros can be a bit too complex to understand it
Salamanders?
Horses won't be used,because every nonsense is already shown as this on the internet...
As hearts is more a "I got no ideas anymore" thing
As mythical creatures,the problem is most are not fitting the mario characters
Cells,bacteria ,I don't know
As a specific pokemon,the problem is dreamup seems to be bad at mixing up two together.
Mario : dragon,insect,sheep,worm,fish(hedgehog,squirrel,dolfin,hamster are still too bad to be shown)
Luigi :