Max is the younger brother of May in the anime. He has not yet received a Pokémon because he's not old enough to be an official trainer, but he became one of Ash's companions and joined Ash, Brock and his sister in order to see new Pokémon in the Hoenn and Kanto Regions.
Max is a small young boy. He has short, black hair and brown eyes, much like his father. He wears a money-green-colored T-shirt with a white collar and button, charcoal-colored shorts and green, black and white slip-on shoes without socks. He also wears black, framed half-moon glasses.
Max may not be old enough to be a Trainer, but that hasn't stopped him from learning all he can about Pokémon before he starts his journey. As a result, he knows much more compared to May, who didn't even know the names of her starter Pokémon's moves. Despite acting mature, Max is prone to being childish should it benefit him.
Max is a genius in the theory of Pokémon training, despite being too young to receive a Pokémon when he first appeared. Both May and Max are the children of Norman, the Gym Leader of Petalburg City and his wife Caroline. Just like any other siblings, May and Max do argue a lot and get on each other's nerves, but nevertheless, they're very close and genuinely love and care about each other, and May's been shown to be very protective of Max. May sometimes gets mad about the fact that Max knows a lot more about Pokémon and training than she does despite not being old enough to be an official trainer. He decided to travel with his older sister and Ash to see even more Pokémon
When Ash arrived at the gym without May in Petalburg City, he was met by little Max, who was surprised to meet a trainer who he had watched on television only weeks ago, through participation in the Johto League Silver Conference. But he also mocked him for losing in the quarter finals of the tournament. He also criticized May for choosing a Torchic as her starter, saying that if he were old enough to be an official trainer, he would've chosen a Treecko.
During his travels with his sister and his friends, Max was in charge of May's PokéNav, acting as a guide. Later on in the series, Max makes a habit of pulling Brock's ear when he sees and talks to a pretty girl, halting his romantic advances as Misty did in Kanto and Johto and the way Croagunk would Poison Jab Brock in Sinnoh for similar effect, dragging him off once incapacitated by the poison.
Max befriended a Poochyena and, although his three brothers who were born at the same time, Poochyena was unable to evolve like them. The only move it knew was tackle so Max attempted to teach it Bite. After a battle with Team Rocket, after using Bite, it evolved.
While Max was walking around in a building with Ash, May and Brock, he accidentally stepped on Poliwag's tail and it immediately came out. After Max apologized to the Tadpole Pokémon, it was revealed that it belonged to the Pokémon Trainer's School in Hoenn. Later on, Max was given Poliwag as he was choosing a Poké Ball for the training arena. It was narrowly defeated by Tommy's Magby as Team Rocket interrupted the match as they were stealing Poké Balls from the Deposit Room. While Poliwag distracted Team Rocket, Magby's Flamethrower burned the Wurmple mecca Team Rocket was on and they were blasted off.
Max is always seen holding a Pokéblock case in his bag or pocket, but May was seen several times getting it out from her bag.
It has been said that Max is too young to get his first Pokémon, but numerous trainers in the show are shown to have Pokémon while they look younger than 10 years old. It's possible that the age limit to be 10 is mostly just for competitions like Gym Battles, Leagues, Contests and Grand Festivals.
Like Misty, Max drags Brock away whenever he falls in love. Max had done this after seeing Misty doing it to Brock.
Max looks somewhat a lot similar to Conway. They wear glasses, wear a green shirt, and have the same hairstyle (although Max's hair is a little shorter).
Max is one of only two of Ash's companions who are not characters seen in the main games, the other one being Tracey Sketchit.