The fight's a stalemate until Nightcrawler get's caught. At which point he's as good as dead. His abilities are largely defensive not offensive. There's a limit to how much additional mass he can teleport and consecutive ports tire him out. It's really just a waiting game for Venom & Carnage. NC's underrated but here he's just outclassed by sheer brute force.
Also sorry for double posting but I'm trying to remember if Nightcrawler and venom ever were in the same comic previously, marvel zombies or venomized bit seem to be likely but I couldn't find anything right away. Any ideas? I need to organize my comics and needed to know if this should be sent in to the cgc for grading and slabing.