Which canon Species could Interbreed/Crossbreed?

[Gaines 1,112]

We know that earth ponies, unicorns, pegasi and alicorns are compatible, but do you believe that there are other races or species that are compatible as well?
I personally believe ponies are only able to breed with other equines, including donkey and zebras, but are incompatible with most other ungulates; they're also incompatible with Breezies and Changelings, which I believe are more like bugs than equines. Any creature that isn't an equine is out of the question to me!

[They call me Loyalty 1,941]

Makes sense to me! But then Discord happened. That must have been one hell of a party.

[Fluttershutter 2,134]

There are mules so pony/donkey is cannon.

In mythology hippogryphs are pony/gryphon but probably not in MLP.

Of course, in reality earth ponies, unicorns, and pegasi would be separate species not even closely related so:  magic. So maybe they can all breed.

So...I dunno.