How old are Wasabi, Fred, Hiro, Honey Lemon and Gogo Tomago?

None of the characters ages are shown except for Hiro's. He is 14 because as Tadashi says to Hiro "Wow. Washed up at fourteen. So sad."

Well since they're all college students we can safely assume they're in the 18-21 age bracket.

Hiro is fourteen, as said in the movie. As for the rest the manga said that they are around the same age as Tadashi, which Disney Wiki says is rather 18 or 21.

Gogo Tomago is 17 in the movie. Hiro is 13.
As for the others, I don't know. You can google it, if you want.