I'd try to stop the whole movie from happening and would've got them to make a 2nd TV series to introduce all the new characters instead of killing off all the best ones. We got ripped off by only getting 2 seasons with the original guys who were the whole reason for the popularity.

Bumblebee.
Now father, you're living in the past. This is the 14th century!
[Formerly CosmosX9]

Yeah, I think I'd pick one of them, too. Probably Ironhide.

Ironhide and Wheeljack
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Skids was pretty interesting. I remember there was one full issue that spotlighted his character in the old Marvel comics. He became friends to a girl that washed him and took him to different nature areas. I think that had something to do with his bio-card being a "naturalist." I can't remember the exact issue but I think it was No. 20
Conquer your fear, and I promise you, you will conquer death.

No one mentioned Skids. He was an underused character that needed more character development. I think he only spoke twice during the second season.
It would have been nice to see the old female Autobots again lead by Elite-One.
What happened to Reflector?

Use the Force.

Thundercracker, Skywarp especially.
I think it would have been really cool to have delved into early Cybertronian War history when it was Megatron, Soundwave, and the 3 jets. I think Thundercracker mentions the Guardian robots "really giving us a pounding" in the episode where they find the Guardian robot body. It would be cool to see more stories about this.
Conquer your fear, and I promise you, you will conquer death.

Yeah, it's fun for me as a Skywarp fan that he was given second life. He does live on.
Would've been fun had the lot of them each had to deal with their former personas like Galvatron-Megatron did.
Esp fun would've had Ghost of Starscream pissed off that Skywarp & Thundercracker are out tearing up the galaxy alive while he's stuck in a tomb lols.
At least I can laugh at that irony, I can't stand Starscream.

Skyfire had an interesting debut and backstory, but then after being on for just a little bit he just vanishes. I always liked Thundercracker's voice and his blue and white color scheme, as with Skywarp he was reformatted so having him back wouldn't really make sense.

For characters who vanished without explanation I'd choose and Hound, and Sky/Jetfire. Two of my favorite characters from the first season.
I loved how Hound appreciated Earth and all it's beauty so much. It would have been interesting to see how he'd adapt to living life back on Cybertron.
Skyfire just always seemed like he had potential as a character but they never utilized him well enough.
As for those who vanished with explanations:
Prowl is my #1 choice. Would have been nice to see him adapt to Rodimus' leadership and how he'd handle that considering he was once Prime's second in command. I don't think his logical brain could handle Rodimus' style of leadership and could create a lot of internal conflicts within Autobot ranks.
Of course this is assuming they'd give the characters proper development which was never a real strong point of the show.
Always really liked Skywarp as well and would have been nice to see him continue but seeing he was reformatted into Cyclonus/ Cyclonus' Armada they couldn't really have the two at the same time.

Shockwave was supposedly meant to die when Unicron's hand came down but he appears and speaks after that point, we don't actually see him die in the movie and he's not referred to as being dead in season three like they did with some of the autobots whom we didn't see die.
Then again Shrapnel shows up again in the movie after he died and in season 3 even has a line of dialogue. There is a miscoloured Shockwave in Five Faces of Darkness not that it counts for much given the huge amount of animation errors in those episodes.

shockwave was killed in the movie.

Tracks, Hoist, Trailbreaker, Skyfire, Shockwave. I wish we got to see more Soundwave. He made a few brief appearances, but wasn't a major character. Which is kinda weird since they gave him new cassettes like Ratbat, Overkill and Slugfest. You'd think they'd want to show them off.

Skywarp does have the best color scheme, hehe.
"Starscream cookies are more than meets the icing!" Nostalgia Critic

Skywarp.
Grown on me as I've got older, seeing what a great Decepticon he really was - being loyal to Megatron, smarter than Starscream, & good in battle.

• he looked cool

Anyone else have favs they would bring back? I would like to see tracks back or hound.

To be fair, unless it was one of the really tough Autobots like Prime or the Dinobots, if Shockwave's gun form hit you, you were probably dead. Despite being a gun, his function seemed mostly non-martial. Maybe Megs wanted someone with offensive capability holding down the fortor maybe the whole "megalomania" aspect meant he didn't want another gun Decepticon there all the time

Except after 9 million years the only autobot Shockwave ever managed to hit despite being a gun was Swoop I think. He really was a lousy shot.

I also would have brought back Shockwave because he might have been a good leadership alternative to replace crazy Galvatron.

I just went by the title of the thread and not the follow qualifier in the thread, my bad.
Hound and Bluestreak also spring to mind but Bluestreak probably met his end along with Huffer outside Autobot city.

Maybe Wheeljack or Smokescreen
Wheeljack is also dead. His body is seen briefly in the movie. Or did you mean anyone who could come back regardless?
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Iron Hide's execution to me is still the must brutal death in the 86 movie
Pre movie. Roller! cause he was such a bad ass! Maybe Wheeljack or Smokescreen

beachcomber was in the series, post movie.
He was in the five faces of darkness.
He was part of the group that failed to protect the ARK.

I agree, Ironhide needs his revenge!
"Starscream cookies are more than meets the icing!" Nostalgia Critic