While it may never happen, it would still be a huge hit if the "Transformers" would meet the "Avengers". Both franchise were among the biggest in the industry and people would probably love watching it. Screenrant made a fan trailer showing the "Avengers" fight the villains in "Transformers".
Earth's Mightiest Heroes was pit against the Robots in Disguise in a fan-made trailer by Screen Rant. They edited videos and clips from the "Transformers" movies already released plus clips and footage from Marvel Cinematic Universe. There were even clips from the movie, "The Amazing Spider-Man", Cinema Blend reported.
Just like the story in the "Transformers" film, the trailers narrates the event where the robotic villains, the Decepticons, are coming down to Earth to get a cubic crystal that would heal their planet. However, instead of the AllSpark, it was tweaked to be the Tesseract which is also called the "Space Stone". The Tesseract is one of the infinity stones in the Marvel Universe. Also, there is a scene where Thor tells his allies about the robot-like creatures which is probably living on in one of the Nine Realms.
After a series of events, which just like a lot of story lines, the Decepticons launches an all-out attack on Earth and the Avengers is the only one that stands in their way. The trailer is full of explosive and action packed moments which ranges from gunfights, missile exchange from the villains and Iron Man, fist fight with The Hulk and even some epic moments with the web-slinger, Spider-Man. There were also a scene showing combination attack from Captain America's vibranium shield and a force from Thor's Mjollnir. There was also a scene where the Winter Soldier shot a grappling hook into Megatron's eye. The video has been uploaded in YouTube last September 4.
Though the movie might never actually happen, there is still a small probability that Marvel and IDW comics should arrange to make a crossover in pages just like DC's "Green Lantern" crossed with "Star Trek" and "Batman" crossed with "Teenage Mutant Ninja Turtles" in comics.