I agree that it would be good to demonstrate character arcs, but I don't believe that every episode would be necessary. We don't need to include every CMC episode, or every episode with Discord, but I do think that we need at least one non-two-parter with Discord, for instance, and I think "Make New Friends but Keep Discord" suffices for that. I feel like it would be better to choose only arc episodes out of those that are good on their own. The Dream Luna arc has a pretty good chance of getting into the guide in whole, but not other arcs.
I disagree on this. The arcs, in full, are what makes the show. While each individual episode may not be important, we need to showcase the full arcs, separated out of the episode lists, so that if one of them is a must-see, then there's a quick resource on which episodes lead up to that.
So, for Season 5 it would be something like.
The Cutie Map - Season 5 Arc
S5E1 "The Cutie Map - Part 1"
S5E2 "The Cutie Map - Part 2"
S5E8 "The Lost Treasure of Griffonstone"
S5E17 "Made in Manehattan"
S5E23 "The Hooffields and McColts"
S5E25 "The Cutie Re-Mark - Part 1"
S5E26 "The Cutie Re-Mark - Part 2"
And the entire Cutie Mark Crusaders looking for their Cutie Marks, from Call of the Cutie in the first season up to Crusaders of the Lost Mark in season 5 should be a list. And an episode could certainly be on more, as I'd have the CMC get visited by Luna in their dreams on both their own list, and on a Return of Princess Luna list that ends, so far, with "Do Princesses Dream of Magical Sheep?"
Just voting on 26 episodes at a time seems like it glosses over things too much. It's too many to give each episode the attention it deserves. I hold the
Clone Wars episode guide as the shining example, pointing out the main story, and giving recommendations to sidestories as they appear. I mean, technically, if someone does not care about the Cutie Mark Crusaders, why is Crusaders of the Lost Mark a must-see?