T. K. Arispe

 Yeah, no, 10 years old is waaaaaay too young to be coming of age.

Takeshi Shudō, the head writer for the first seasons of the Pokémon anime, wrote some novelizations of the first episodes of the anime where he went more in-depth about the society of the Pokémon world as shown in the anime. In the anime universe as Shudō envisioned it, people were legally considered adults at age 10, which is why Ash and Misty can romp around Kanto without any adult supervision, and why 10 is the minimum age one can be registered as a Pokémon Trainer.

Shudō's novelizations also included a lot more character background than was shown in the earlier anime, including the reason why Misty is so acerbic toward Ash (she spent most of her life around other girls and her first real experience with a boy was when she beat one up for being mean to one of her friends), and why Brock is so awkward around women (his mom abandoned the family due to the stress of being a Gym Leader, so he's subconsciously looking for a girlfriend who can make up for his lack of a mom).

These novelizations are very obscure, out of print, and were never published outside of Japan, and as nothing more has ever been officially said about them, I think it's safe to say The Pokémon Company does not consider them canon. I think it's kind of a shame that more material from them didn't find its way into the anime, because one of my frustrations with the early anime was that the character development was a little shallow. 

It would have helped to have backgrounds and explanations for the characters--and it also would have helped to show them grow and overcome their challenges rather than perpetually using their quirks for gag comedy. For example, maybe traveling with Ash and Brock could have helped Misty realize that not all guys are terrible, and there could come a point where she admits to them that they're the best friends she's ever had. And maybe Brock could have finally come to terms with his parents and realized that instead of looking for a "new mom" for his inner hurt child, he needs to move forward, give himself the parenting he never got growing up, and work on obtaining and maintaining a relationship that's beneficial for both himself and the other person. I think that sort of character exploration would have helped make the show more watchable for adults, too.

It's too bad that the early anime kinda eschewed character development in favor of comedy and trying to make sure they included all the Pokémon. I can't help but feel like that approach to writing the show was what got the writers in trouble when the original plans for the GS Ball were unexpectedly shelved. Without multidimensional characters to carry the show until they could come up with a replacement story arc, the anime hit unarguably its lowest point with scads of thin, formulaic filler episodes in between not-terribly-interesting Gym battles.

Making a franchise-based anime is challenging in the first place, but you should never paint yourself into a corner by creating characters who can't hold their own, writing-wise, no matter what the parent company throws at you. The writers finally managed to right the ship near the end of the Johto saga, and I think the writing in the show just kept improving after that, but those first few seasons remain kind of a cautionary tale for me.