>>137236937Whilst I can't recall if they're ever given a proper clarified age, episode 49 (Role Models) has the Mayor giving Sonic and co trophies for saving the village one million times. Running the math, if they're defeating Eggman (or even other villains) once every single day, they'd be roughly 2740 years old. If it's twice every day, then they're roughly 1300+. If it's split between each member once per day, then you're still looking at them being approximately over 500 years old. And if it's twice but still split, then it's around them being 274 years.
And if you massively round-down based on the punch-card the Mayor shows instead for Hero rewards, then Sonic alone is still 18, Knuckles is around 19, Amy is 15, etc. There's also the fact that canonically, they were intending for the Ancients in the Boom continuity to have been the OG cast, and who knows how THAT works.