I think early teen or mid teen is best. I feel like I can relate to the character more, since I'm around that age now.
Id say Mid to late teens. I really dont want to play as a 10-11 year old, Id prefer the player character to be at least a little a few years older.
I'd say around the 16-18 mark. Saving the world as a 10 year old is fine as it relies on the strength of your pokemon not yourself. Leaving home,, however, is a different story. How many pre/midteens do you know who would be able to look after themselves properly on this adventure? Very few kids at that age could fend for themselves. (I am aware some could.) Not to mention, school. If kids are leaving school at 9 or 10 is it any wonder the police have to rely on a young child to sort everything out? Your only option in life would be pokemon because you'd be qualified for nothing else. How the Joys ever got to be nurses with that kind of education, I'll never know. Anyway, I'm rambling so sorry. Really it's a fictional game so these things can be overlooked but yeah, I'd say around 16-18.
I honestly don't mind. For some reason, However, my headcanon is that as of Black and White, the characters are the following ages:
Gold (Ethan)/Kris/Lyra/Silver: 12-13
Hilda/Hilbert/Cheren/Bianca: 13-15 (Headcanon, people. I have a problem with them being older for reasons unknown to me and everyone else.)
I also believe that Black and White take place at the same time as XD:Gale of Darkness. Personal headcanon.
Long story short, I really don't care. My protagonist can be 10, 3, 65, or immortal.
I'd prefer for them to keep bumping up the age as the fandom grows up, but I'm not complaining. I do think they need to make a game for older audiences, though, and have the characters be around 18-20.
I agree that there should be an option, just like there is for gender. Though I don't mind if they want to keep it at 10-ish, I think it would be a neat option.
To be honest, I don't really care. I accually kinda liked being a 10 year old in the games, you know?
I could be playing, like @Shadow Victini said, I also don't care if the main caricer is 4, 20, 44, 102, or even a dog for that matter, I still like it.
They should make it into an option, yes. I don't particularly mind, but my personal preference is 14-16.
Well, I guess we still have Wes and Lucy Fleetfoot. (Although nobody counts the latter because she's from a puzzle game.) And Wes is pretty awesome.
And the B/W protagonists look slightly older.
Although for all we know, they could be older or younger.
I'd say 13-14, probably. I don't want them to be too old like 16-18, but not prepubescent like 10-12. Although this answer is subject to change.
Mid-teen, somewhere close to 15. Much more realistic, and still an ok age for the target audience of kids.