Deadpool's immortal healing factor ultimately defeats Batman's tactical genius — you can't strategize against someone who won't stay down.
This is brains vs. regeneration, and it's a fascinating matchup. Batman is arguably the greatest tactical mind in all of comics, with contingency plans for defeating gods. Deadpool is an unkillable mercenary who has literally fought his way out of the afterlife multiple times.
In a straight fight, Batman would dominate the opening exchange. His combat skill is arguably superior to Deadpool's, his gadgets give him range and versatility, and his tactical mind would let him identify and exploit Wade's fighting patterns quickly. Batman would 'beat' Deadpool within the first few minutes.
The problem is that Deadpool gets back up. Every. Single. Time. Batman can't decapitate him (he regenerates), can't knock him out permanently (healing factor), can't contain him easily (he's broken out of everything). Batman would need to find a way to permanently neutralize the healing factor, which requires prep time and specific knowledge he wouldn't have in a standard encounter.
With prep time? Batman wins. He'd research Deadpool's weaknesses, engineer a solution, and execute it flawlessly. Without prep? Deadpool wins by attrition.
Batman's combat skill, gadgetry, and tactical intelligence would let him decisively win every exchange. His utility belt contains EMP devices, freeze grenades, and sonic weapons that could incapacitate Deadpool temporarily. With prep time, Batman has defeated beings far more powerful than Deadpool. He is the ultimate problem-solver.
Deadpool literally cannot die. Batman can 'win' the fight a dozen times and Wade will crack a joke, reassemble himself, and come back for more. Over a prolonged encounter, Batman's gear runs out, his stamina fades, and his human body takes damage that doesn't heal. Deadpool's body does heal. Attrition always favors immortality.
Without prep time, Deadpool wins through sheer attrition — you cannot permanently defeat what cannot die. Batman would absolutely dominate the actual fighting, landing cleaner hits with better technique, but Deadpool would keep regenerating until Batman physically can't continue. With prep time, Batman finds a way. He always finds a way.
Batman also fights
Deadpool also fights