The simple reason for the improvement is Misty - the female character in Ash's gang - is replaced by May, a young beginner trainer who begins her Pokemon travel at the start of the anime, not much later Brock is returned and May's little brother joins the gang. the big change in May's appearance is not that she is much better than Misty, not any fans will say that and even me, but still her role in the Advance series is much larger than Misty - if Misty was only served as the company of Ash without effecting much the adventure of Ash and the series, May's role is much larger since her reason to travel is to be a coordinator and show her Pokemon in contests than gym battles, her choice to do that is filling the series in more important episodes except the usual Capturing and gym battles episodes with contests and grand festival episodes, besides that even the "filling" episodes feeling much more connecting to the main story to be an unnecessary episodes ("filler episodes"), and not just this but Ash also have much more mind in his Pokemon battle and raising it's Pokemon.
But all that not change the fact that the Advance series is such a good series - three full seasons is only on the Hoen league and the Hoen grand festival while the final season of the Battle Frontier somehow has much more important episodes but however have more problems than the first three seasons, to make the comparisons I will divide this review to two:
Hoen league Arc
One of the good things about the big arc of the Advanced series is like I said above, it contains a lot of important episodes, from the first gym battles to contests battles and the capturing Pokemon episodes, unlike Misty who caught a Pokemon only in a while, as May is a beginner she has a lot of room in the anime to make her Pokemon team, not only that but Ash also not disappoint and except for some Pokemon he evolved all of his team.
Not that alone, the gym leaders have a lot of room in the Arc to be explained and a lot of development even before the gym battles, which makes them a lot more interesting to watch.
But all that aside, the Arc still suffering from "Johto episodes" that comes to time to time, but what makes the Arc better is that those episodes are much rare than it was in the Johto seasons as I said above, the contests and the grand festival episodes making this Arc much better.
Though that to be said, the contests episodes and battles feeling much less tense and thrilling than the Gym battles and the League episodes, though their necessity and preferring them above the filler episode, they don't feel like canon episodes of the Advanced series and have a feels of "come to fix Johto seasons problem".
Battle Frontier Arc
In Battle Frontier Arc Ash and his friends are going back to the Kanto region, or much more accurate, they meet again after a short splitting in the Kanto region, from Pallet Town again for two goals: for Ash to conquer the Battle Frontier and May to win the Kanto grand festival by gathering five ribbons all over again.
Before the review I will introduce a little thing about the Battle Frontier, in the games, the Battle Frontier serves as the post-game materials, in the games, all the Batlle Frontier's facilities are placed in one big island west to the Hoen region, the point of the Battle Frontier facilities is to challenge the player in Maze quests or different ways of Pokemon battling in challenging way to test the Player knowledge, one example for that is the Battle Factory, which the player not using his Pokemon at all but choose between three different Pokemon, testing the knowledge of the player in abilities and types of Pokemon against NPC random player who using also three-to-choose Pokemon, after a couple of winnings in the facility, the player is battling the Frontier Brain who like the player using random-pokemon-to-choose, once winning him the Player gets the Knowledge Symbol that presents the Facility challenge.
Now let's get back to the anime, in the anime as I said, Ash and his friends already split only to be rejoined in the next episode to continue traveling again, it makes the same feeling as the Battle Frontier in the games is - only a post-game after the League and nothing more: the story isn't that interesting and the battles at the Battle Frontier are much less intense, the rules for each facility are much less rigid than the Gym battles and the "excitement in the air" to beat the Battle Frontier isn't there as to win the league.
But that's not my point, my main point is that the Anime ver. to the Battle, Frontier is the worst adaption ever seen not only in the Pokemon anime but in the anime ever. if in the games the battle frontier facilities have much more point on testing the trainers abilities the battle frontier in the anime is as Scott the founder of the battle frontier states - "like" gym leaders, while he says "like" the facilities is more "unofficial gym" than a battle frontier facility that designs to test the trainer, the only fact that they are "much stronger than gym battle" is of course since Ash just win the Hoen league gyms and if they weren't strong that strong what will make Ash go to them?
Though it may be a real bad adaption, it makes sense once you say the reason - the studio didn't really mean to create the Battle Frontier season but just to not make more "fille episodes" and to stretch more episodes on the Hoen league, so they only created this Arc to wait 'till the diamond and pearl games to release, in their actions of that they actually said - "if we will make much more accurate adaption of the Battle Frontier for the games, we will make more seasons only for that since it's requiring more than one season to do that, and we don't want to since we don't really need it, and it's not that interesting", though I didn't read officially statement it's clear from the rush "feeling" of the arc.
And that rush "feeling", though make this arc much more eventful actually make it worse - though every 2-3 episodes there's a contest or battle frontier battles this "rush" make the things made the Hoen arc good to bad - the Frontier Brains are much less introduced and even those who are much developed not so interesting; not only that, though it's Battle Frontier arc, the winning of the battle frontier feels much less necessary and meaningful than win the league, even to win the grand festival feels much more important and meaningful to "beat the battle frontier", which makes this season though more eventfull to less interesting.
Story - 9
Now to the characters.
Ash feels much more confidence in the advance series, no more "friendly gym leader" or "not to think" strategy and touch of luck, Ash really trains his Pokemon not only in theory but dedicate his time to raise them well, this makes Ash much more than "guy who loves pokemon" to a strong trainer, although his personality didn't change much, it's much more interesting to watch him in this series.
May, though to be Misty's replacement, is more girlish than Misty either in her attitude or her look, but with that being said she still has some "tomboy" in her, though not to be likable like Misty, she's still much more effecting the story.
Max who joins the group, has some mystery effect fading off in the series, in the start his smartness makes him useful and has much more effect on the story, but with time his importance is fading away quickly and feels like "extra character" than even supporting character.
Brock, though returned for the series is a good point, feels in some way more of "supporting character" than main, if in the previous series his ideology and his guidance feels necessary for the story and Ash, feels now only the "cook guy" who helps from time to time, his appearance in the series let me feels like he can be with some other groups of trainers and do the same things, his "sick of love" feels more important than his supporting the story.
Though Ash doesn't have the main rival in this series except for his league temporary rivals May has two main rivels except for temporary ones, one is Drew, which in the start can be rude and evil, as the story continues he feels much more like stubborn-friendly rival than evil, in his replace for evil-rival she gets Harly that not just evil but rude and cunning.
Team Rocket didn't change at all from the Johto seasons, and though being funny from time to time, their stubbornness is still annoying, though for some episodes James can be interesting enough to still the show, Jessy stubborn to take part in the contests don't help Team Rocket much.
Team Aqua and Team Magma, on the other hand, not only interesting but feels much more canon than Team Rocket, though the adaption of them can be much better.
Character - 8
The Art, though being "feels" better does good only on the character designs, but the backgrounds still feel like child paint, in the Battle Frontier season though it's getting better but only slight improvement.
Art - 7
The sound didn't change much than the previous seasons, but still enjoyable.
Only one note on the dub, although I have already gotten used to the Pokemon company dub, in its start on the Battle Frontier season it's pretty horrible and even Sarah dubbing Ash doesn't sound like the Ash I know from the newest season, only in the last few episodes of the series there's some improvement, but May's and Max's voice annoyed me a lot in this dub.
But if we talking about the voices, one of the annoying things in the dub is the narrator getting replacement halfway through the first season, but returned in the new dub for the Frontier season, and that was actually one of the good things I admired about the new dub, the new narrator 4Kids got was not only as good as the old (or rather, the known one) but his narrating feels as he didn't wanted to get the job but forced there, at some episodes it even feels as he's bored from Pokemon and his narrating is not as exciting and interesting, that is actually one of the good things I enjoyed hearing when watching the Frontier season, and the usual narrator doesn't fail.
Sound - 7
Enjoyment\Overall 8\8 - though the Advanced series still has problems, it's much more enjoyable than the Johto series with good character development and better animation.
