Olimar's son is introduced in Pikmin 1 in the log book, along with the rest of the family, including their dog Bulbie, and in Pikmin 2's space e-mails. It seems that he wants to visit the Planet of the Pikmin, and was upset that his father went back to the planet a second time without him. His e-mails imply that he really admires his father's being a Space Captain.

Pikmin Characters
Captain Olimar | Captain Louie | President | Olimar's Family | Olimar's Wife | Olimar's Son | Olimar's Daughter | Louie's family | The President's Wife | Bulbie | Olimin | Alph | Brittany | Charlie | Character D