>>56317215Kanto
Red and Blue are 11 years old as Generation I, and 14 years old as of Generation II.
Red's age is mentioned, and Blue is said to be the same age as him, in the player's story from the Japanese and English manuals of the Generation I games (except their ages are not mentioned in the English manual of Pokémon Yellow).
"You are an 11-year-old boy living with your mother. Your rival lives next door to you. [...] He sees you as his rival because you are the same age and height."
Primo is 27 years old as of Pokémon FireRed and LeafGreen.
His age is mentioned in the Japanese song "Teach Me, Poké Dude!" from the Pokémon FireRed & Pokémon LeafGreen: Super Music Collection.
Johto
Ethan, Kris, Lyra, and Silver are about the same age.
The Poké Maniac in Cianwood City appears n Black 2 and White 2, despite the timeskip between the games.
"If you've made it this far, that means you've won 14 in a row. What a fluke! Fourteen is how old I am! Ha ha ha..."
Queen Bellelba (fictional character portrayed by Sabrina) is going to be 108 years old in the current year, as of her appearance in the Mystery Doors of the Magical Land Series from the Pokéstar Studios in Pokémon Black 2 and White 2.
Queen Bellelba mentions her age as part of her dialogue in the Strange Ending version of the 3rd episode ("Open a Door"), only if the player is male:
"Even though my beauty is overwhelming, I'm going to be 108 years old this year."