Spider-Man (and i think some other Marvel superheroes) appeared in Marvel's G1 TF comics; more recently, there was the New Avengers/IDW TF crossover.
Spider-Man and the Fantastic Four are two examples i know of Marvel superheroes who have been known to travel from one universe to another.
G1 Cliffjumper has travelled to a parallel universe (Shattered Glass); G1 Jackpot and G1 Hubcap have travelled to a parallel universe (Axiom Nexus); and Armada Over-Run was one of several Transformers travelling to a parallel universe in DreamWave's "Worlds Collide" series.
With all of the above as evidence that the following scenario is possible: What do you think would happen if the Transformers encountered the Marvel Zombies
Would the Marvel Zombies be able to eat and/or infect the TFs? How much trouble would the TFs have defending themselves from the Marvel Zombies? Would any of the TFs try/succeed at curing the Zombies? Would any of the TFs (presumably Decepticons, unless we involve SG-type Autobots) try to use the Zombies as a weapon/distraction against their TF foes? Would any of the TFs (perhaps G1 Shockwave) be curious about the Zombies' unique "energy sources" and try to render a TF-compatible version?
On a semi-related subject, i'd be curious to see what would happen if the Marvel Zombies got to Axel "Access" Asher