From Bulbapedia, the community-driven Pokémon encyclopedia.
Isamu Akai (赤井 勇) nicknamed Red is the protaganist of the Pocket Monsters manga. He is based on Red from the original Pokémon Red and Green. His surname contains the Japanese word for "red" (赤 aka).
In the anime
Red and Clefairy's anime artwork.
Red makes a cameo appearance in the Pokémon anime in Lights, Camerupt, Action as a character in a short movie along with his Clefairy and Pikachu.
In the manga
Red is a young trainer from Pallet Town who received a Pokédex from Professor Oak and was sent on a quest to find out more about Pokémon.
Red encounters a violent male Clefairy on his way to Professor Oak's lab, and together they defeat a giant Nidoran♂ by accident. When Clefairy follows Red to the laboratory, Red chooses to travel with the Clefairy because he finds his antics amusing.
Unlike his rival, Red doesn't catch a lot of Pokémon. He has two (later three) favorites, which he keeps outside balls. However, he caught several others, including Articuno, but never used them.
He continues his journey in Pocket Monsters RS, the sequel of Pocket Monsters that takes place in Hoenn, and in Pocket Monsters DP, the second sequel of Pocket Monsters that takes place in Sinnoh.
His rival is Kai Midorikawa.
This is a list of Isamu's known Pokémon in the Pocket Monsters manga: