I'm looking to introduce the Transformers cartoon continuity to someone, but don't want to make them slog through everything. My goal is to put together a concise, must-watch list that captures all of the key story points, with a few iconic character-building episodes along the way. Material will be drawn from:

Seasons 1 + 2
The Movie
Season 3
Headmasters
Masterforce
Victory

So what's your watch list and order?

 

Obviously MTMTE parts 1-3 are in there, as well as Transport to Oblivion.

 

War dawn, The Rebirth, Five faces of darkness, The key to Vector Sigma, The rebirth of Optimus Prime, Forever is a long time coming, Dweller in the depths, Bruticus's Revenge, Starscreams brigade,

 

Speaking from the S1 - S3 only, I would have him watch the following (and limit it to 35):

MTMTE Parts 1-3
This goes without saying as it gives an excellent narrative to the majority of the cast

Transport to Oblivion
Followup to MTMTE and adds continuity for Transformers as a mainstay on earth. Plus it introduces the Space Bridge; an integral part of the first two seasons.

S.O.S Dinobots / War of the Dinobots
I couldn't decide on whether to add either this or the Ultimate Doom trilogy, but the Dinobots are more impactful to the series overall. Plus, it's kinda the first new Transformers introduced in the series next to Skyfire. It's best to see how they came about than just seeing them "appear" and having your friend ask more questions.

Heavy Metal War
Introduction of the Constructicons and combiner technology. Has a couple of rivalry type fights based off the previous episodes listed (Megatron v Optimus, Dinobots v Constructicons)

Dinobot Island Parts 1 - 2
This is essentially the episodes that introduce most of the Season 2 characters in the Transformers mythos.

Atlantis, Arise! / Microbots
There's no particular reason these episodes are listed as it has no continuity to the overall series. However, they're wonderfully animated and the scripts are decent - I would avoid any Akom animated episodes whenever possible. Plus, drunk Decepticons which was subsequently deleted in future airings in syndication.

Megatron's Master Plan Parts 1 - 2
Definitely one of the better schemes from Megatron in a myriad of 80s cartoon villains. Perfect blend of S1 and S2 characters

The Search for Alpha Trion
This goes without saying. Introduces female Autobots, Alpha Trion, and the hint of him being the creator of Elita-One and Optimus Prime

The Key to Vector Sigma Parts 1-2
Introduces more combiners, more Alpha Trion. Based off my order, this is the first appearance of Omega Supreme. If he (or she) starts asking questions about him, you could add The Secret of Omega Supreme, but then we have to go through that whole Constructicon origin nonsense. Better off waiting to explain that.

War Dawn
Finality bridge of S2 Alpha Trion, more backstory on Optimus, and characterization of the new combiner team. Great episode.

Starscream's Brigade / Revenge of Bruticus
More combiners, the struggle of Decepticon leadership, the rare Autobot/Decepticon team-up. Small dosage of S1 characters.

Transformers the Movie
Bridge between S1-2 and Season 3. A must watch

Five Faces of Darkness Parts 1-5
I'm not really a fan of this five part series, but as an introductory expansion piece of Season 3, it's best to view this 5-parter. If your friend asks why the animation has gone to s#!t, explain later.

Dark Awakening
Somewhat return of Optimus Prime. One of the better S3 episodes

Webworld
I honestly think that the script was way ahead of its time here. Focuses on Galvatron's sanity or lack thereof, and address the issues directly. For what it's worth, Webworld starts the S3 music, and I'm a huge fan of a lot of it.

Starscream's Ghost / Ghost in the Machine
Akin to showing Optimus, it might be necessary to know Starscream's fate and his mythos in the Transformers Universe. Starscream's Ghost is technically out of order with Webworld, but no biggie here.

The Dweller in the Depths / The Ultimate Weapon / Call of the Primitives / Burden Hardest to Bear
All good episodes in their own right with Rodimus leadership struggles sandwiched here and there. More Quintesson mischief, Metroplex v Trypticon rivalry, the cartoon "origin" of Unicron. These four episodes are among the best Season 3 has to offer in terms of animation. There are a couple of others like Chaos, but I left that out.

Return of Optimus Prime Parts 1-2
The actual return of Optimus Prime. Might want to explain to your friend how these episodes came about.

Other notes:
Probably the only episodes I regretted to add were any focus on the Insecticons. Also have him subscribe to Transformers At The Moon on YouTube.

 

More Than Meets the Eye

If your friend can take this, you can probably show him/her as much or as little of the rest as you like.

If your friend has trouble sitting through MTMtE, just skip directly to the movie and then done.

If the movie sparks your friend's interest, you can give the series another shot. If your friend isn't won over by the movie, it's not even worth bothering to try anything else. It's not for everyone and you shouldn't try to force it on someone, any more than you'd want a friend trying to push some goofy cult or veganism on you.

 

All great recommendations so far.

Agree on this point. The series takes some changes in tone as it progresses, so I think there are a few jumping on and off points.