I am going to be contributing another Transformers Pure Evil and it is one I already did on TVT and covered on another wiki.
What's The Work
Transformers/Back to the Future is exactly what it says it is, a crossover between the Transformers and Back to the Future franchises.
Who Is He And What Has He Done
Megatron as usual is the tyrannical leader of the Decepticons. Now due to it being a Back to the Future crossover, it involves a lot of time travel stuff so there are actually two Megatron's the two are the one in the current timeline and the one in the Crapsack World Alternate Timeline I for this proposal I will only be talking about Alt!Megatron since the other one doesn't do much.
Due to the manipulations of a time-travelling Rumble and his enslaved human collaborator, Biff Tannen spent ten years stockpiling Energon cubes, and in the year 1984 Rumble broke into the Ark and reactivated Megatron and all of the other Decepticons prematurely. Megatron would kill off Optimus Prime and without him to stand in his way Megatron quickly conquered the world killing most of the Autobots and forcing the rest underground. He would also murder Rumble for seemingly no reason and used Biff Tannen to enslave all of Hill Valley forcing the population to mine and murdering them whenever they failed to meet Megatron's quotas, as well as per usual killing anyone who opposed him.
By the time of 2015 Megatron's sheer level of cruelty eventually got so bad that it caused Gigawatt to turn on him. Megatron attacked him intending to kill him but Gigawatt was able to escape just in time but not before Megatron was able to damage his Flux Capacitor preventing him from travelling.
After this Megatron isn't really seen again and is eventually erased when the timeline is restored.
Redeeming Qualities/Mitigating Factors
Nope, none to speak of in terms of the character himself but there are a few things I need to talk about. First of all, since this is a crossover with Back to the Future you may wonder if it's played seriously well it is since it is more based on the transformers' style of tone.
Now Offscreen Villainy is something that needs to be mentioned since Megatron as a villain is very distant to the point where the heroes never ever encounter him. However, we see many of his actions and personality in actions wth him speaking and stuff we see him killing a majority of the Autobots before they wake up and him attempting to execute humans for failing to meet their quotas something which he has done many times. And while we don't see everything he does we see the effects of it with Hill Valley being a dystopia where nearly everyone is enslaved in the mines by Biff who is under orders from Megatron or at least the Decepticons which Megatron leads.
No problem he has many murders enslavement of an entire town and likely many more and executing any human who fails to meet their production quotas as well as anyone who is no longer useful to him. Everyone else like Biff is just working for him. He isn't exactly the most heinous baddie or version of Megatron out there but I think he does do enough to stand out, this crossover as far as I can tell also seems separate from the rest of the franchise.
A yes in my mind.