Where do I start? Hmm….Spike, Fluttershy, Applejack, or Starlight Glimmer.
Spikes episodes tend to be between horribly boring and sloppily designed, or are just outright atrociously bad altogether. It took the writers SIX SEASONS to make so much as ONE good episode, and to this day, Gauntlet of Fire has been the only good Spike episode to exist.
Fluttershy used to be a lot higher on my personal ranking for the main six, but ever since realizing how all but one of her episodes are exactly the same, she has since fallen into dead last. Aside from Flutter Brutter, can you say she has any episodes that aren’t the same ‘she’s too shy to do this one thing, so she has to overcome her shyness to beat it’? Flutter Brutter is the only focus episode she has that DOESN’T continue the trend of her being a one-trick pony, pun intended. You’d think the writers would learn to not have to rely on the exact same gimmick all the time for one character, but if that were the case, Fluttershy’s episodes would’ve been getting substantially different since probably season three.
Applejack gets the least amount of screentime overall, so it feels like she has a lot of focus episodes herself, when she really doesn’t. However, the majority of her episodes have to exaggerate her flaws and also include majorly done to death tropes about farmer characters. Either way, they usually arent all that good.
Then comes Starlight Glimmer. The majority of her episodes are awful on account of the things that Starlight has to have happen for her to look good at all, most of which involve having to shove entire characters aside and forcefully bask her in the sun, where she doesn’t belong. If she isn’t abusing her magic and causing chaos/ruining lives, she typically doesn’t even have to be involved in the episode at all, serving as a completely meaningless object needed to force the plot along. Every Little Thing She Does is an allegory for the entirety of her career on screen; all previous characters basically get completely annihilated in order for her to look good, her magic defies any level of sense or reason, Twilight has WAY too much blind faith in her to not panic and make a bad problem worse, and ultimately, she gets completely forgiven without even the remotest chance of her learning anything, especially when she does something completely, utterly, inhumane.