Objectively speaking, Ash isn't bad trainer or "failure at life". As some like to call it.
He may make mistakes sometime. Forgett in heat of excitement and desire to win obvious things such as physical moves not affecting ghost types or electric attacks not hvaing effect on ground pokemon. He can be rash and unwary at times too being impatient in challenging other trainers or going into danger by himself ending in trouble because of that(one of examples from current series was in episode about Heliolisk robot with Clemont saving him).
However Ash also proven time after time to posess great deal of creativity and out of framed standards line of thinking, Coming up with most unusual strategies completely confusing gym leaders and trainers of high calliber winning because of it. With those who have years of experience under belt being impressed and widening their horizons because of this.
Ash was merituous for several times saving world or certain part of it from catastrophe by stopping rage of legendary pokemon(including pokemon God itself Arceus).
Stopped villain organizations. Consistently qualified for pokemon leagues going on higher brink with each new region. With exception of anomaly called Best Wishes.
Most of all Ash won numerous competitions, conquered Orange league championship, Frontier brains being offered even place to be part of prestigue Battle Frontier. Organization accepting to test out only most promising and adept trainers out there.
Ending recognized by several high class trainers which represent and mean something in pokemon world such as Agatha, Drake or Bertha from E4, champions like Cynthia, several gym leaders and strong trainers like Tyson, Tobias, Paul, Gary, Harrison etc, etc).
With Ash persistence, determination in accomplishing what he has on his mind, huge passion and strong emotional bonds he creates and strengthen over time making him material for champion. And one day pokemon master achieving his long term dream eventually.
Im of opinion how issue lies in pokemon anime having sorry to be blunt terrible continuity and inconsistency in staying faithful to character development.
Demonstrated through Ash stagnation and regression depending from saga to saga.
Zero connections to past generations almost never bringing up Ash past achievements, wins and various activities and challenges which supposed to leave effect on character. Changing because of that.
All of past experiences and older friends(see Misty, May, Max etc) being left forgotten in past never brought up again. Their friendship with Ash, impact they left on him in maturing and progressing as trainer accompanied with unresolved goals, unexplored issues and abandoned stories going way of GS ball. Becoming plot holes in Ash long journey and chasing after career in hopes of fans just forgetting and stopping to care.
Pokemon anime repetitive nature not having any stable cast through which past experiences of Ash and started development could be transfered to next generations. No attention payed to amount of growth and hard work happening in previous series underrmining Ash credibility as trainer. And very scattered, basic development with Ash still not making more substantial, further steps in his journey.
Giving out false impression of Ash being "weak trainer".
When in reality its exact
opposite with writers lack of motivation in changing status quo, lack of attention toward past and marketing restriction to extent hindering his development and story progression. Shame, in older series it felt like this show still had direction to follow and on going plot through which relationships, development of characters and journey was built upon.
His character was flawed, but that was what made him so interesting.
Now he is just plain, boring and lacking personality and emotion though.
I wouldn't say Ash doesnt have any flaws or personality nowadays though.
Ash showed plenty of personality in newer generations too. He can be brash, impulsive and hotheaded. He has big appetite, can be laidnack not paying attebtion to details. Full of persistence and competitive spirit in overcoming any obstacle brimming with energy and optimism when hes up against strong opponent. Entangled with unselfish, loyal and deep care for his pokemon.
Sure he seems more decisive, responsible and perhaps wiser in this day and age. But thats in my opinion more so maturity and character development he went through. Which is supposed to add on, rather than taking away from character in reality.
Not to mention way Ash will act also depends on environment and type of people he is currently surrounded with,
Its to expect that he wouldn't express same emotions, reactions and outburts to current Kalos cast which is mostly cheerful, friendly, kind and supportive unconditionally. Like he used to with some past companions/friends(Misty, Gary, May to lesser extent come to mind) who could make him agitated, drive out some of his sarcastic, fiery side from character.
Or deliver wider stream of expressions ,making current cast dynamic feel still too one dimensional and static imo(but ill leave this thoughts for another day and time).
Are there characters who might break that mold? Most certainly. There are very talented Trainers who for one reason or another choose not to participate in the Gym Leader Challenge. That is not common, though.
I would also like to add how several trainers of high calliber may choose not to enter league simply because not everyone is interested in reaching fame or some high status. Being driven by such passion, competitive flare and determination to win tournaments, catcgh as many pokemon as possible and defeat strongest ones.
Passing of as unnoticed but highly competent trainers.
Than there are also talenbted indivuduals which pursue different careers not battlin gym leaders. For example Iris wants to become dragon master and while not all tasks were revealed she needs to overcome to gain that title. Winning regional league isn't one of them.
With Misty who wants to become water master insted of league, there were showded to exist prestigue elemental tournaments you need to win to come closer and achieve dream(like Whirl Cup which is often overlooked). Along with wishing to reach E4 strength like Lorelei she idolize both in anime and games(and by becoming E4, while there certainly must exist special tests to pass collecting badges isnt required).
Coordinators like May, Dawn etc of course striver towaerd winning Grand Festivals reachjing expertise through different type of events etc).
Point being how chasing after badges and qualifying for league isn't only clear indication of whether someone is skilled, adept and perceptive as battler. But its certainly most known measure in pokemon world.
