I'm wondering if an Earth pony with mechanical wings could join, or perhaps an Earth pony who is half pegasus since they might have a bit of pegasus magic in them.
I've watched everything from all gens except for season 2 of Pony Life. Normally I tough it out if things are bad but Pony Life always produced the same thing each episode and it was just so forgettable. As for the FiM show itself, I never dropped it because even though there were bad episodes, they didn't ruin my impression of the show.
For animation, 2D works the best since you can use more cartoon logic and it won't offend as much as 3D cartoon logic, even if we're talking about magical ponies here. Not only that, but 2D ponies are easy to replicate and they look much cuter.
It is too bad that Luna felt obligated to retire with Celestia since like most people are saying, Luna could've ruled for a thousand more years on her own. They also could have at least given Twilight some training before they threw her into ruling.
She probably took "friendship is magic" too literally since she had interpreted it as a means to obtain power rather than to have an improved quality of life. She had probably tried making friends in the past but couldn't keep them for long since she didn't have a purpose for them.