- "See you, Space Cowboy!"
Andy has a tall, thin build, very similar to Spike's. His blonde hair is grown out and fluffy. In keeping with his adopted cowboy character, Andy invariably wears a full cowboy costume. This consists of a white coat and chaps, grey double breasted shirt, jeans, grey gloves, and a large red ascot. The costume is completed with a large traditional grey cowboy hat.
Andy is also rarely seen without his horse and constant companion, Onyx. He uses Onyx as his primary means of transportation, often riding him into buildings or even up elevators.
Following his fight with Spike, Andy abandoned his cowboy character and adopted the character of samurai Miyamoto Musashi. He appeared in the final scene of the episode wearing a samurai-style kimono, riding his horse, which he renamed Jiroumaru.
Andy is a rich, incompetent, self-centered, stubborn and selfish bounty hunter.
He later on develops a new code, following the code of a samurai and dons a new look.
Andy's main combat skill is the use of his Colt Single Action Army pistols, which he carries two of. When hunting bounties, his primary tactic is simply to confront his target directly and attempt to bring them in at gunpoint. While he is proficient in the operation of his single action pistols, he seems to have little skill in actually hitting targets. When facing Spike on the rooftop of City Hall, he empties his pistols during the fight, hitting nothing. During his early chase involving the Teddy Bomber and Spike, he fires his shotgun style grenade launcher at Spike indiscriminately, hitting multiple buildings. This recklessness in no doubt the cause of his many destruction of property charges.
Andy also appears to have basic hand-to-hand combat skills. He is able to attack and avoid Spike for several moments during their final battle. By using his environment, he actually appears to get the better of Spike. However, due to his character and the way he handles himself in battle, it's more likely that his successes are the result of dumb luck and Spike's lack of composure.
Born into the wealthy Oniyate family, Andy used his family's wealth to facilitate living his life as various character archetypes that appealed to him. For a good portion of his time as a bounty hunter, he has assumed a cowboy character. He was a member of the Young Men's Cowboy Association for a time, but was kicked out for his ineptitude and recklessness. His blundering style caused hundreds of cases of public and private property destruction, as well as numerous injuries.
Andy met Spike as both attempted to apprehend the Teddy Bomber, who was bombing buildings around Mars. Just as Spike is about to take the Teddy Bomber, Andy bursts through a window on his horse, claiming to have cracked the Teddy Bomber's pattern. He accuses Spike of being the Teddy Bomber, having been fooled by Teddy Bomber's guard disguise. Andy's interruption gives Teddy Bomber the opportunity to detonate his remaining bombs, destroying part of the building and allowing him to escape.
Andy's next appearance is at a costume party being targeted by the Teddy Bomber. Entering the party on horseback, Andy accuses first Jet then Spike of being the bomber, despite having met Spike the previous day. Once again, Andy's interference allows Teddy Bomber to detonate his bombs and escape. This time, Andy manages to chase Teddy Bomber away from the scene. With Faye tagging along, Andy starts to pursue Teddy Bomber through the streets of Mars. However, Spike joins the chase in the Swordfish, distracting Andy completely. Forgetting the Teddy Bomber, Andy fires at Spike without regard to the destruction he's causing to surrounding buildings. 
Possibly by design, Andy bears a very strong physical resemblance to Spike. They are nearly identical in almost everything besides hair and eye color. Andy and Spike are the same age, and only have an inch of height difference. This is most likely deliberate, as one of the main themes of the episode is the comparison of Spike and Andy's personalities and methods. Jet, Faye, and the Teddy Bomber all describe them as having the same trouble-prone styles.