Underrated Ponies.

I always liked Cherry.

Twist. Where did she go? Into the background because she had a cutie mark. We never see her and AB interact again. Same problem with DT and SS - they fade into the back once they’re no longer villains.

Minuette. She was a treasure, but they didn’t use her.

Flitter. Does anyone remember her?

Cheerilee. She had a lot of potential input in CMC plots, but she wasn’t used to the extent she could have been. The persistent hints that she’s single and unhappy didn’t go anywhere. And she was mostly obsoleted at the end by the friendship school.

Rainy Day and Appointed Rounds

Apple Strudely

Spring Step and Lilac Sky

I love Flitter! She’s just so adorable.

At Mare Fair somebody was going around with a clipboard polling people on their favorite and second favorite ponies. I put Flitter as my second and was told I was the only person who had ever mentioned her.

I also love Lily. She’s adorable too.

Silverspeed. It’s strange how the fandom never noticed this one.
She appeared (and was called by name) in one of the best episodes of the show (Hurricane Fluttershy).

You’re absolutely right! She is criminally underrated.

Sapphire Joy and crystal ponies in general.

The show really skipped over their story potential. The many trips to the Crystal Empire always focus on ponies from Equestria, with the crystal ponies being reduced to extra-stupid background ponies.

Very much agreed! I hadn’t even thought of that! Even if the episode still has to feature Equestrian characters (which, virtually every episode did), they had plenty of room to tell stories in the Crystal Empire. And the Friendship Map gave the writers the perfect opportunity to do that since you just need to ship two viewpoint characters off to an exotic location and let the locals carry the rest of the episode. And it would have been very easy to make a Crystal Empire episode since the worldbuilding has already been done.

But no, instead we got more episodes in Ponified New York.

I often like to joke that the Crystal Empire became an Equestrian puppet state, but your statement reminded me of these old posts from Derpibooru:

Good short fanfic, only 1000 words.