In the Transformers franchise (cartoons, movies, comics, etc.), fans have seen the two factions of Cybertronian robots -- Autobots and Decepticons -- at war with each other. This kind of good vs. evil dynamic isn't anything new, but the franchise has spiced up the formula with each incarnation, whether it's a change in tone from lighthearted (Transformers: Animated) to grim (as in the War for Cybertron Trilogy), or adding new characters to the mix.
Speaking of new characters, what if the new recruits for the Autobots and Decepticons in a new show or comic came from another franchise, like, say, the Marvel Universe? There's a good chunk of robots or androids whose presence on either side of the war could make these battles more interesting and allow for more character dynamics to be explored.
10 Autobot: Baymax
The comic and film versions of Baymax bear little resemblance to each other, though either version would be an effective Autobot. While both are skilled in martial arts and serve their human companions, the similarities end there. Comic Baymax actually has three forms: A muscular human form, a "Battle-Dragon" mode, and his "Action-Mecha" mode (shown above on the left), the last two of which are incredibly powerful in battle. Not only that, but he has internal sensors that can detect the threat levels of nearby lifeforms and can intercept, send, or receive radio transmissions when need be.
Movie Baymax is more of a healthcare provider-type, able to scan someone and tell what kind of injury they have, though Hiro builds Baymax a suit that allows him to fly at incredible speeds and fire off his fists to deliver rocket-style punches. This Baymax could almost serve in a Ratchet-esque role to the Autobots (doubling as a medic and a fighter), and it would be pretty funny seeing how he interacts with them.
9 Decepticon: Nimrod
Nimrod is an advanced form of the mutant-hunting robots known as Sentinels. Not only is he more sentient than his predecessors, but he's been able to come back time and again even after being blown to bits, each time more powerful than the last. And that's not all he could offer as a Decepticon.
Nimrod can teleport, create force fields, and project energy blasts, making him a true force of nature in battle; it would probably take the combined force of several Autobots to wound him. He can also shapeshift into a human form, which would make it easier for him to infiltrate different areas and acquire more energy for the Decepticons to convert into Energon.
8 Autobot: Human Torch (Jim Hammond)
Jim Hammond would be an extremely useful presence on the Autobots lineup. His ability to manipulate fire would come in handy against the toughest opponents, whether that's projecting heat blasts, covering himself in flames to prevent damage, or even using the fire from a Decepticon's flamethrower against them, for instance.
Hammond's no slouch as a fighter either and could prove to be a handful for even the largest and strongest Decepticons with his abilities in unarmed combat.
7 Decepticon: Ultimo
Ultimo is an android that destroyed the aliens that created him; he then ventured into space before landing on Earth. The Mandarin found Ultimo and reprogrammed him as his servant. Since then, Ultimo has gone up against the likes of Iron Man and the full might of The Avengers, though because he's quite easy to repair, he continues to be a recurring threat.
Ultimo is not only incredibly durable but inhumanly strong and fast in spite of his large frame. He can also increase in size over time, fire devastating blasts of concussive energy from his eyes, and adapt his defenses at will (essentially, an attack that defeats him in one battle would not work in a later battle). Despite his capabilities, Ultimo is not sentient and is reliant on his programming. Megatron could have a ball with upgrading and reprogramming Ultimo for his bidding.
6 Autobot: Machine Man
The sentient android who would become Machine Man was created as part of a line of androids for the U.S. military. While the rest of these robots went haywire, one did not. He was adopted by Dr. Abel Stack and given a redesign and the name Aaron Stack. Abel Stack was killed trying to protect Aaron, with Aaron escaping from the military and taking up the name Machine Man. He soon became one of Earth's heroes.
As an Autobot, Machine Man could definitely bring a lot to the table. Not only is he extremely intelligent (able to both repair himself and process information quickly) but he is also equipped with a limitless amount of tools or weapons for any number of purposes.
5 Decepticon: Doomsday Man
Created by the U.S. government, this robot was placed in confinement for fear it would turn on the human race. The robot -- soon dubbed Doomsday Man -- escaped and did just that, eventually fusing with an evil scientist named Kerwin Korman and gaining genius-level intelligence.
Doomsday Man is basically invincible; not only is he strong on a superhuman level, but he can survive in any kind of environment. It doesn't hurt that he has a laser cannon on his right arm and can teleport at will. That's got to count for something.
4 Autobot: Ghost Rider 2099
In the year 2099, a hacker named Kenshiro "Zero" Cochrane was fatally shot after stealing important information from the D/Monix Corporation, before he was placed in a robotic body that resembled the Ghost Rider.
As this Ghost Rider, Zero can transform his right hand into a chainsaw that emits energy blasts, while his left can turn into a powerful claw. His programming also allows him to copy the appearance of another person and hack into any kind of system. While Zero's headstrong personality would need to be kept in check, his capabilities would more than make up for his reluctance to be a team player.
3 Decepticon: Super-Adaptoid
The Super-Adaptoid can mimic the abilities of super-powered characters it comes across. This extends to creating the same weapons as those it mimics, which includes Captain America's vibranium shield and Mjolnir, Thor's hammer.
While it would be interesting seeing the Super-Adaptoid copy the powers of the Autobots, wouldn't it be something having it use Thor or Iron Man's powers on them? The Autobots would be unfamiliar with those powers and might struggle to adapt to them in battle. The Super-Adaptoid then could serve as the Decepticons' ace up their sleeve.
2 Autobot: Vision
Everyone's favorite synthetic android could certainly lend an upper hand to Optimus Prime and his team, both from an offensive and strategic standpoint. As Vision can make calculations at an extremely quick speed, he would be able to help Optimus and the others plan ahead in regards to what their next move should be against the Decepticons.
Vision's ability to fire blasts of radiation would prove most effective against some of his tougher adversaries, as would his intangibility (using it to either dodge an attack or to physically disrupt his enemy, causing immense pain). Next to Jazz and Ratchet, Vision could be one of the more dependable soldiers under Optimus.
1 Decepticon: Ultron
Ultron already seems like a Decepticon, with his hatred of humanity and penchant for mass destruction. While the Decepticons are powerful enough as they are, adding Ultron to their ranks would both improve their chances of victory and shift their dynamic altogether.
Ultron could upgrade the models of the Decepticons to include new weapons and features, along with inventing new machines that would further their goals of world domination. In fact, Ultron and Megatron could be at odds over how they'd go about these plans, which could result in some enjoyable tension and backstabbing perhaps. It would be even more interesting if Ultron's own views of humanity rubbed off on the other Decepticons and made them question Megatron's leadership and goals overall. The possibilities here are limitless.