«Lost» episodes is a crazy idea, but it can work for a show with a separate story for each episode — honestly, a lot of episodes from original
FiM could be put into another season seamlessly, except for small details like CMC trio with cutie marks or Twilight’s castle. After all, I remember an anime named
Non Non Biyori, where the creators put the Season 2 episodes between the Season 1 ones... and they did the same again in Season 3, so it looked like they just expanded the first season with new fillers.
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Equestria Girls? If they have some unused ideas, let them finish the show.
At least, unlike their pony counterparts, the most of main cast never had their sneezes. Only the lucky lavender-coloured nose was tickled once, and that’s all

.