Mostly based on character development though.
1) Autobots and Decepticons realize that there are newer, better models of their altforms. What they didn’t realize is how gorgeous some of these newer models are. How would Sunny and Tracks react to the Reventon and the ZR1, respectively? What about the Seekers and the F-22? And Soundwave with an mp3, such as the iPod? And how would some 'bots react to the new cars such as the Bugatti, Koenigsegg, and Concept Camaro?
2) Sparklings are not something that Cybertronians love and want. In fact, they are considered too “organic” and are a source of great disgust and shame, because they are the byproducts of the Quintessons experimenting with the early Transformers with organic reproduction in mind. Any mech/femme that has a sparkling or is pregnant with one is immediately treated as an outcast, even if it was an accident and they themselves don’t want it. So..
---a. One of the TF get pregnant accidently.
---b. Reaction of the TFs when they see human young for the first time. What did they think/do when they saw babies? Toddlers? Daniel?
---c. One of the 'bots used to be a sparkling. How did they go through life as an object of hatred? (This would be really interesting if it was someone highly respected, such as Optimus Prime.)
3) Jazz is Prowl’s creation, but doesn’t know it. He feels a connection to Prowl and that’s why he tries so hard to be friends. Prowl, in turn, tries to avoid Jazz as much as possible, because of shame (he had Jazz when he was very young, and abandoned him - something that he regretted) and fear of Jazz finding out the truth.
---a. Reverse, with Prowl as Jazz’s creation. Jazz is trying very hard to make up for past mistakes and Prowl wondering what he did to deserve a stalker.
4) TFA/G1 Xover: In the middle of a battle, the Decepticons are winning and Sari wishes for help. The key provides. G1 Optimus Prime, Prowl, Jazz, and Ratchet (or anybody else, but OP needs to be there) is transported to the TFA ‘verse, and it all goes downhill from there. Mostly thinking of character development, with the TFA characters learning from the G1, and maybe even the Elite Guard’s response thrown in (especially Sentinel’s to G1 Prime).
5) In Vos during the early stages of war, Starscream is NOT a prince or anyone of high importance. … Officially. Unofficially, he controls everything from the background, with the real prince/council as mere decoration. Megatron (and possibly Shockwave/Soundwave too) goes to Vos to gather Seekers, and quickly discovers that the “high council” is a sham. Starscream proceeds to lead him on a whirlwind chase from the shadows, with the vow that, if Megatron can find the TRUE leader of Vos, the Seekers will join in the war. To make it worse, he has to dodge loyal supporters and the Autobots (who are also there). (Stems from the fact that Starscream’s intelligence doesn’t get enough credit. He’s a scientist and SIC. He’s not there because he’s pretty.)
6) Beast Wars: Everyone in BW only knows the Great War from holovids and stories, except for Rattrap. Despite his laidback and sarcastic attitude, he’s almost as old as Ravage. One day, during an exceptionally bad battle, he’s forced to use nearly all of his skill, which surprises the ‘bots enough to start questioning him. Bonus for:
---a. Rattrap was a Decepticon.
---b. He was a rather famous TF of the War. (Like Sideswipe, Bumblebee, Shockwave… This could also lead to some background info on how he became Rattrap.)
---c. Relationship changes. Would OP/Rhinox begin listening to him more? Would Dinobot start to respect him and give less backtalk? How would the Preds react to finding that the Maximals had a Great War veteran among them (especially if he used to be a Decepticon)?