Character interactions that didn't happen in tfa that i think would be amusing:
Jazz and Wreck-Gar. I think Jazz would look at the funny Al Yankovic garbage truck man play his silly tunes and he'd go "damn bro you have some goofy tunes I like that".
I've said it before but Bulkhead and Blitzwing having an art related interaction, either friendly or talking trash about each other.
Porter C. Powwel and Swindle. They're both so greasy separately that putting them in the same room would probably manifest actual grease dripping down the walls.
Jazz and Soundwave, this one speaks for itself.
Honestly just more of the jettwins, they would definitely get along with Sari and Bumblebee.
Sentinel interacting with any of the bots created from allspark shards, he would have a fucking stroke.
In the same vein Sentinel having to deal with the goofy human villains, he would have an even bigger stroke.
Soundwave and Shockwave. Would they get along? Would they try to kill each other? Or would they just quietly seethe but not actually fight because that would inconvenience Megatron.
Also Soundwave and Blitzwing, they could do a little dancey dance together