I liked to think that deer or even reindeer should be shown in season 5. They have the whitetail woods, so I would that it was named after an old deer settlement that once lived there.

What species do you like the most or should be considered for canon? (I'll accept bat ponies but I think they should be given a proper name.)

Mexicans

Sapient cervines, the pony equivalent of Elves and Fey people, Changelings before they became Changelings, Thestral/Bat Pony (Pretty much already canon), Sea Pony, the pony equivalent of dwarves and pixies, etc.

Bat-ponies.
With the proper name of Bat-ponies. Or Nightwing Ponies. I thought that was a good name. Much better than some ripoff of Harry Potter.
Or Stygian, since that references mythology, as much of MLP does. I'm less opposed to that nowadays.

Also, Moth-ponies and proper sea-ponies.

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I would like to see the flutterponies along with their revamp Queen Rosedust

I want Sea ponies! And Flutter Ponies. There wasn't a lot of good MLP when I was little, but those were fun. (I was a G2 kid).

Dears and Caribou, also sea ponys!

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Przewaslki's Horses; the presence of the Saddle Arabian delegates and the references to horses makes it clear enough that at the very least some of the most archaic and distinct horse breeds exist in Equestria, if not far many more than that. I want this fact explored in detail.

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Emus

3971676 the Equine Pixxies ould be the Breezies? which of the two types?
3971676 Unless they state that the Sea Pony isn't Canone, I go by them still being around.
As to the Bat Pony, they could be Vampire Ponies as well, all depending on the aspects.
3971743 Love the Night Wing, they are after all nocturnal, right?
3971809 Unless they go back on them, I go by them still staying Canon too.
3972000 Loved the old seasons preFiM too, even if they were slow on follwoing up and never made all that many episodes.
3972750 Deers have hooves, like Cow, thus they should be considered, right along with technically, pigs, even if we see it as a far stretch?
3994990 Oh, never forget the Horses. in MLP, they apparently are not Ponies. Different type.

3971597 I kinda really want to see more predators. Bring in the cheetahs!

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I think they should introduce a predatory species, preferably with a society. Bat ponies seem to fit well, but they would be (for the most part) peaceful. Maybe more changeling breeds, or monstrous subspecies of Fairies (fairy includes breezies, sea ponies, batponies, etc. in my mind, as although they are separate they are powerful pony-esque creatures)?