Pretty much the season that gave us the first unambiguous Accusation Fic episode, Season 2 only built upon the first while introducing season finale that is still talked about today for all the wrong reasons.

What episodes deserve a revisit and why?

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Well, I'd flag Mare Do Well as the first big one, not the finale, but you do have a fair point that it's been largely forgotten lately since Rainbow's flanderization in canon has driven most of the people who cared about her out of the fandom.

Ponyville Confidential. I still thought it was uncalled for for Rainbow to kick a storm cloud on top of the crusaders.

I'm voting for "A Friend in Deed" and "Dragon Quest"; Pinkie Pie's incessant badgering and stalking of Cranky Doodle is one of the first examples of how she can't seem to take 'no' for an answer and how she believes her beliefs are universal truths. And in "Dragon Quest", it shows how the Mane Six seem to see Spike's dilemma of not knowing how to be a dragon as a joke or the fact that he doesn't measure up as one, rather.