* First Equestria Girls movie happens between season 3 and 4, but I'll leave out EQG mentions from here on.
* Twilight is a princess now. She has a nice song about her doubts.
* The Elements of Harmony came from something called the Tree of Harmony, which over the course of the series gains more sapience, until it actually develops an avatar that looks like Twilight Sparkle.
* It turns out even when he's good, Discord is still a jerk. He actually has a pretty long and subtle story arc of chilling out over the course of the series. Eventually he becomes close friends with Spike and Big Mac, and has a pretty heavily implied crush on Fluttershy.
* Daring Do is real and becomes a recurring character. It's weird.
* Pinkie's sisters are properly introduced, and they're all super popular. Maud especially, despite not actually being in Pinkie's season 1 flashback.
* Twilight has a freaking DBZ fight with a villain named Tirek, who destroys her library. It gets replaced with a castle.
* It turns out the castle is connected to the Tree of Harmony, which displays friendship problems on a map. Using this, they discover a cult run by Starlight Glimmer and stop her. One of the former cult members, Sugar Belle, later dates and then marries Big Mac.
* Rarity opens stores outside Ponyville, each with its own supporting cast.
* There's an episode focused on background ponies like Derpy, Dr. Hooves, Lyra, and Bon Bon.
* The Cutie Mark Crusaders got their cutie marks. Other songs in that episode are really good too, BTW.
* Yaks are introduced as a recurring species.
* Starlight uses freaking time travel to get revenge on Twilight. Twilight friendships her. Like with Discord, her reformation actually lasts much longer than this song implies.
* Cadance and Shining Armor have an alicorn baby, Flurry Heart. She's a force of destruction. If you're wondering, no, this still hasn't gotten an explanation.
* Starlight's childhood friend Sunburst becomes a pretty major recurring character.
* After screwing up in season 2, they eventually revisit dragon culture and make it, well, not junk. In particular, Dragon Lord Ember (formerly Princess) becomes a recurring character.
* Trixie becomes a recurring character, and Starlight'slove interestbest friend.
* Rainbow Dash joins the Wonderbolts. It's oddly underplayed.
* By season 6, they mostly stop having "Fluttershy is shy" episodes. She's consistently pretty assertive in her focus episodes.
* They introduce a good changeling, Thorax.
* Starlight, Trixie, Discord, and Thorax defeat Queen Chrysalis. The latter takes her place as ruler of the changelings, and they all transform into brightly colored forms once they accept friendship.
* Fluttershy and Rainbow Dash's families are both introduced. Fluttershy has a younger brother (who is an adult, not a colt), Rainbow is an only child.
* Celestia and Luna actually start getting focus episodes.
* Apple Parents shown in a flashback.
* One of the best songs of the show not already linked happens.
* Starswirl the Bearded and other ancient heroes are brought to modern times. Starswirl turns out to be a jerk, but he's friendshipped.
* The Movie happens. Despite no characters from it showing up again (except for Capper in the background once), it has surprisingly big repercussions.
* Hippogriffs are introduced as a recurring species. They can transform into seaponies.
* The Mane Six decide to open a school to spread friendship, so something like the Storm King's invasion won't happen again.
* The Student Six are introduced: Gallus the griffon, Smolder the dragon, Yona the yak, Silverstream the hippogriff, Ocellus the changeling, and Sandbar the earth pony. They end up having connections to the Elements of Harmony too.
* The next villain is Cozy Glow, a normal filly that joined the school but then decided to drain all magic from Equestria.
* The newest villain, Grogar, has gathered all the other living villains together for a plan to be enacted in the series finale. They have a song.
* Celestia and Luna are retiring, and Twilight and the others will take over for them. This has been the season long arc.
There, with more info than needed, yet still leaving a lot out.
Congratulations. When I saw that they wanted a recap since Season 3, I instantly gave up. I think the only major thing missing from your recap is you don't make it clear how significant and prominent a character Starlight is. She's not at quite the level of the Mane 6, but she's at least at Spike's level.
