Trixie's Secret Revealed?
Spoiler
Oh yeah, several! They've had several encounters with "intelligent ponies"--
A Unicorn named Unique with a dragon assistant named Thorn was stealing gems from local cities. There was a battle where the Drow unleashed a barbarian pegasus with blue feathers and a really insane speed score. Then there was the summoner purple unicorn that fought the PCs as a chance encounter at Castle Ravenloft.
Currently there's a reoccuring green pegasus artificer that keeps annoying the PCs on occasion with her oddball inventions.
So yeah, we fought ponies.
Time to fill the swimming pool with insulin. Again.