Ash: 13 (They had to change his clothes now that he's a teenager. Then again, he might be 12, but that depends on whether or not the short before Pokemon 3 occurred in Johto. If it did, then that would mean that Ash is twelve going on thirteen.)
May: 10 (I stand by this - puberty is said to occur earlier in girls than it does in boys)
Max: 8 (maybe even 7)
Jessie: 22
James: 20-22 (I personally think that James is younger)
Brock: 18 (He was fifteen at the beginning of the series)
Tracey: 17 (I think that he was a bit younger than Brock)
Richie: 13 (Same Age as Ash. They could have been twins, dammit >_<)
Oak: 63 (I heard something about 60 being Oak's age at the beginning of the Anime. Whoever said 52 was off by a couple of years)
Gary: 14 (I think that Gary turns fourteen sometime midway through AG, him being a couple of years older than Ash.)
Misty: 14. I think each of her sisters, unless they mentioned someone being the oldest, are all triplets, and they are all 22-24.
Delia Ketchum: 31-33.
Norman: 33-35.
Can I go to gym leaders now? There are no proof of these, except for speculation on my part.
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Brock: 18 (as mentioned earlier)
Misty: 14 (as mentioned earlier)
Lt. Surge: (at the time of gym match) 40-45
Erika: 22-25
Koga: 45-50....scary...
Sabrina: Early 20's. Her father wasn't dirt-old, so...
Blaine: Damn...do I even have to answer this one? He's older than Oak. No questions asked.
Giovanni: 50s. He keeps himself well-groomed, so I believe that he could be in his 50s.
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I'll do Orange Islands once someone reminds me of all four
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Falkner: 16 (at time of Gym Match)
Bugsy: <13 (C'mon...if anyone so much as thinks that he was a day older than 13, I'll sledgehammer them into the ground.)
Whitney: 19 or so..(then again, considering how May was all...developed...at 10, Whitney might be 15 or 16.)
Morty: Possibly my favorite gym leader. He will have had to be about 24-28, IMHO.
Jasmine: About the same age as Whitney. These look like two girls who were best friends in High School.
Chuck: ~45: (He really let himself go...)
Pryce: 65. (Anime has a habit of making people look older than they really are. Plus, he mentioned something about his Piloswine disappearing at a timeframe of 50 years ago. He looked like about 15 or 16 in the flashback.)
Clair: Definitely 25-27.
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Um...I think that Professor Birch and Professor Elm are the same age (Elm might be younger as a matter of fact), but Birch can be more physical when he has to, and Elm...well, Elm's just a nerd who probably already has a receding hairline.
Norman: 33-35, like I mentioned.
Roxanne: 17-20
Brawly: 16-21 (I offered a bigger range, because with those surfer guys, you never can tell.)