Brendan is a tall, thin young man with brown hair, a white hat, pale skin, and dark eyes. In the Generation III games, he wears a black headband with a red PokéBall pattern. He sports a long-sleeved red and black sweater and black pants with yellow cuffs at the bottom. His sneakers are also red and black, matching his outfit. Around his neck he sports a gold band with a round white circle in the center, and on his hands he wears yellow and blue palm gloves. In Emerald, his clothes have some gree...
Brendan is a tall, thin young man with brown hair, a white hat, pale skin, and dark eyes. In the Generation III games, he wears a black headband with a red PokéBall pattern. He sports a long-sleeved red and black sweater and black pants with yellow cuffs at the bottom. His sneakers are also red and black, matching his outfit. Around his neck he sports a gold band with a round white circle in the center, and on his hands he wears yellow and blue palm gloves. In Emerald, his clothes have some green patches.
His appearance changes slightly in Omega Ruby and Alpha Sapphire. He appears to have tanned skin, and gray eyes. The style of his headband is slightly different than it looked in the previous games. He wears a red and black short-sleeved shirt and black and gray shorts. He wears a green backpack and white and green sneakers. He has a Mega Bracelet on his left wrist.
(Source: The Pokémon Wiki)