Venom vs. Superman
I think you are thinking about DC vs Marvel. Superman is having trouble restraining Venom, until the spiderman clone shows up. Batman didn't meet any X-Men in that, but did clock Bull's Eye.
I think I am talking about the second series where the X-men show up at Dr. Strange's house where Batman is investigating, and they duke it out until the JLA arrive. Then they merge into the X-league.
Been a couple years, so I could be wrong.
CES