Is there a limit to the amount of different species that a Lyaric can be? Like if I wanted to mix 3 different species would that be okay?

And are there any species that are incompatible with eachother and can't be mixed?

Traditionally, Lyarics were only a mixture of two species — but this was for ARPG registry / coding reasons.
Now that we no longer have an ARPG aspect, you are welcome to mix as many as you'd like.
We will not reject any designs that are submitted into the group (unless it's someone submitting like, a Warrior Cat OC, y'know).
And no, there were no species that were incompatible.