Sure he is athletic enough, but let's look at his qualifications.
First of all, Batman has too many aids. He has cool cars that when smashed up transform into fat wheeled motorbikes. Where would he put all the dog crates and trial gear?
His outfit has things fly off for various reasons. He's got wings for goodness sake. Wings would be totally distracting to a dog. Proper attire is absolutely necessary for agility. I'm not sure, but it is a good guess he'd get disqualified on his gear belt alone. What about Batmans gloves (if that doesn't look like a dog toy, I'm a 6 foot tall supermodel!)?
From all accounts in this last batman movie, dogs don't seem to like him, but they do like crazy clown faced wackos. I think it is due to his facial expressions and voice. Dogs like silly happy voices, not Darth Vader voices. They also like to read your facial expression. To all accounts, batman is a really angry kinda guy, but the Joker seems sorta happy in his own way.
I don't think that Batman has a systematic handling system. He seems more like the "seat of your pants" kinda guy and in agility, that is just asking for trouble.
But I tell you. He could get over all of the above disabilities to a good agility handler, if he wasn't so self absorbed. He truly believes that he is the only one that can "get it done," and that my friend is the kiss of death in agility. One must trust and accept the partnership before one can excel in the area of the teeter, jump, and a-frame. A loner does well to stick to sports that do not rely on teamwork.