"Omega Red is a mutant with superhuman strength and the ability to emit lethal pheromones from his body (death spores). These spores result in the weakness or death of humans in his near vicinity. The severity of the effect is based on the endurance, health, and relative proximity of the victims. Normal humans would be killed in a matter of seconds of exposure, while beings with heightened endurance can withstand it for minutes or hours."
"Omega Red has the ability to drain the life force of other humans to sustain his own. Omega Red can do this by ensnaring his victims within his tentacles."
Red's death spores would be useless against Venom.
His death factor would require Red to ensnare Venom in his coils. And it's still debatable as to the effectiveness of the death factor against a symbiote. Regardless, as good as Red is, I don't see happening against a level-headed Venom out for blood.
Wait a second. Current Venom? Nevermind. Red wins regardless of the effectiveness of his death factor.