Transformers vs Ben 10

Connection:

Both are iconic animated intergalactic alien conquerors who wanted to take over their worlds out of a twisted sense of love for them (Cybertron and Vilgaxia respectively) as both deeply care for their races despite what their overall cruelty might suggest and took the fight to Earth

Both known for having tons of robots, bounty hunters and weapons at their disposal and have battle forms that are basically less humanoid versions of their normal forms (Megatron transforms into either a gun, tank or stealth bomb, whereas Vilgax can unleash his true form which is a giant squid)

Both have silver-tongued yet cowardly right-hand men that either plotted to take over their role or just follow them out of pure fear (Starscream and Psyphon respectively)

Both are considered the arch-enemies of the iconic transforming main protagonists (Optimus Prime and Ben Tennyson respectively), who are equipped with one of the powerful cosmic devices that would be essential in defeating them (The Matrix of Leadership and the Omnitrix respectively) from wise centuries-old aliens who are renowned for their intelligence and act as guides to them (Alpha Trion and Azmuth respectively) and are the star players of organizations of intergalactic peacekeepers (The Autobots and the Plumbers respectively)

Yet despite their immense hatred for their rivals, they have put their differences with the heroes aside and teamed up to defeat greater threats in the past

Both also interacted interacted with extra-dimensional demonic beings (Unicron and Dagon respectively) and were transformed into their heralds for a time until they regained full control of themselves

Both also were also voiced by Fred Tatasciore in one of their video games (Punch Time Explosion and War for Cybertron respectively)