This is my first time drawing Sonic stuff since then. And I came across something in the process.
There have been a few attempts at mobianizing the ponies, but all they REALLY NEED, is the nose bridge. They don't really need a completely separate muzzle, just so long as you have that bridge between the eyes, it works.
Beyond that, give them the average mobian proportions and round heads. Add their EqG boots for bonus speedible effect, and you're good to go.