This variety is a list of possible versus scenarios between heroes and villains alike from all universes.
Venom vs Clayface: both have shape shifting abilities and can pose as anyone they choose. If there was a winner I believe it would be Clayface. While Venom is an alien symbiote, he still has to have a human host (Eddie Brock or Mac Gargan) and while Basil Karlo was human, he's more clay than he is man.
Dr. Doom vs Vandal Savage: Both are very intellectual and cunning villains in their own respect, one is immortal and has (in varying sources) been a conqueror/leader throughout history and the other has his own country. Both in different aspects have been leaders of supervillain teams/organizations; Vandal with the Legion of Doom in Batman: Doom and Dr. Doom with Marvel's supervillains in Marvel Alliance. In terms of who would win, it be slim and could go either way; possibly in terms of who has the better tech (personally I think Doom would have that advantage). However, it would lean more towards Vandal because Dr. Doom does have a bit of an ego. Either way, the end result would be 50/50.