At least, out of the "main gang." Mickey, Minnie, Donald, Daisy, Pluto and Goofy never age. But Max was preteen on Goof Troop, a high schooler in A Goofy Movie and a college student in An Extremely Goofy Movie.
Max is voiced by Jason Marsden, who's voice acted in a lot of childhood favorites. He was Kovu in The Lion King II: Simba's Pride, Haku in the English-dub version of Spirited Away and Chester McBadbat on The Fairly OddParents.
Though Jason Marsden can sing, Disney wanted to go with someone a little more "Broadway" for Max's songs. Aaron Lohr (Newsies) provided Max's singing voice, and, fun fact: He recently became engaged to Idina Menzel, aka Elsa from Frozen.
There are nuns in the background in almost every new location that Goofy and Max arrive at. They're on the highway at the beginning of the road trip, at Goofy's store (*cough*KMART*cough*), at a baseball game, at a diner and even at the Powerline concert.
11. There Are Two Shout Outs To 'The Little Mermaid'