Over the course of his entire Pokémon journey, Ash Ketchum has taken part in numerous Pokémon League competitions, with it taking him until the Gen VII region of Alola for him to win the Manalo Conference and his first league title. Ash usually puts together strong teams of Pokémon that fight their way to try to achieve victory for their trainer, but equally, Ash has faced many individual Pokémon that have caused him serious problems.
The best and strongest Pokémon in these environments of the tense Pokémon League contests are those that are able to showcase their power while conserving energy, having the stamina and strength to eliminate multiple enemies before being knocked out themselves.
10 Katie's Walrein Is The Tough Final Hurdle For Ash To Get Past
The Ever Grande Conference in Hoenn is well remembered, due to Ash having three colossal 6-on-6 matches that each tell their own captivating stories. The first of the 6-on-6 bouts see Ash face a trainer named Katie, who quickly establishes her use of strategy and type superiority.
Katie makes things difficult for Ash, but it gets worse when she calls upon her final Pokémon, Walrein. The bulky Ice Break Pokémon picks off Ash's Swellow and Corphish, before frustrating Grovyle with the same hit-and-run tactic, using the water to retreat and adding a sense of unpredictability to its attacks. It is only undone when Grovyle tricks it into freezing the water, leaving it out in the open and leaving it vulnerable.
9 It Takes Infernape Activating Its Blaze Ability To Defeat Paul's Electivire
Over the course of Ash's entire rivalry with Paul, one Pokémon, in particular, is seen with the aggressive trainer more often than not. That Pokémon is Elekid, with it evolving first into Electabuzz and later into Electivire.
Electivire is a boisterous Electric-type that specializes in both physical and special offense and has always been a formidable opponent whenever Ash has faced one in the anime. In their quarter-final match, Paul's Electivire beats both Pikachu and Gliscor, before losing out to Infernape when it makes use of its Blaze ability.
8 Ash Underestimates Cameron's Riolu And Ultimately Regrets It
Ash's loss to Cameron at the Vertress Conference in Unova is often considered one of Ash's worst-ever performances, with the battle itself being sloppy and largely underwhelming. Despite only bringing five Pokémon with him due to his own incompetence, Cameron is able to defeat Ash, with his Samurott defeating Pignite, Hydreigon beating Boldore and Oshawott, and his Riolu sweeping through three of Ash's Pokémon.
Riolu evolves into Lucario while fighting Snivy, having already defeated the disappointing Unfezant, and proceeds to also beat Pikachu for the win. It may be considered a Baby Pokémon, but Riolu embarrasses Unfezant before unleashing its full potential and getting through the rest of Ash's team.
7 Harrison's Blaziken Is A Formidable Introduction To The Hoenn Region
When Ash faces Harrison at the Silver Conference, he gets to experience two Pokémon from a region he has yet to explore, Hoenn. While the initial surprise of facing the unknown Kecleon is quickly dealt with by Ash's Pikachu, Harrison finishes the bout with his Blaziken, which proves to be more than a match for Ash's Charizard.
Having already put a stop to Ash's defiant Bayleef, Blaziken outlasts Charizard in an explosive clash of Fire-type starter Pokémon, giving a brief glimpse of what can be expected from the Hoenn region, Ash's inevitable next destination.
6 Alain's Bisharp Helps To Carve Through Ash's Team, Ready For Charizard To Finish Them off
For all of the credentials that Alain's Charizard has, Alain's Bisharp ends up registering just as many knockouts as the Mega-Evolving Pokémon does in the final match of the Lumiose Conference against Ash. The dual Steel-Dark type showcases its brutal physical offense by cutting through Ash's Hawlucha and Goodra before eventually falling to Greninja as the battle reaches its final stages.
Ash takes Bisharp for granted, and, before he knows it, Bisharp has helped to drastically reduce his team and ultimately helps Charizard to emerge victorious through the final stages of the battle.
5 Tapu Koko Joins Kukui's Team To Face Ash
Tapu Koko is a surprise addition to Professor Kukui's team during his exhibition 6-on-6 match with Ash, after Ash wins the Manalo Conference in Alola. Tapu Koko takes a strong interest in Ash and Pikachu throughout their whole journey across the Alola region, so with hindsight, it makes complete sense that it would be the final hurdle for Pikachu to overcome.
As a guardian deity of Melemele Island and a Legendary Pokémon, Tapu Koko is Kukui's final Pokémon and defeats Ash's impressive Ultra Beast Naganadel before turning its attention to Pikachu and taking it to the limit in an explosive affair.
4 Paul's Drapion Takes Out Half Of Ash's Team & Poisons The Other Half
Given Ash and Paul's fierce rivalry throughout the entirety of the Diamond & Pearl series of the anime, it isn't too surprising that the two have several battles leading up to their final bout at the Lily of the Valley Conference quarter-finals. Paul manages to either win or draw against Ash in every battle prior to their final encounter, but never uses the exact same team due to his ruthless nature as a trainer.
In their Sinnoh League battle, Paul calls upon the help of his Drapion, with him not having used it against Ash before. Drapion proceeds to wreak havoc on Ash's team by using Toxic Spikes to poison any Pokémon switched into the battle, shifting momentum in Paul's favor. Drapion is able to take out half of Ash's team in Buizel, Staraptor, and Torterra before it is finally stopped by Gliscor.
3 Latios Completes Tobias's Destruction Of Ash Despite A Spirited Display From Pikachu
After Ash's Sceptile is able to finally put a stop to Tobias' Darkrai in their semi-final bout at the Lily of the Valley Conference, Tobias once again defies expectations by this time bringing a Legendary Pokémon to the table. Latios is able to make short work of the tired Sceptile, as well as Ash's Swellow before being given more of a fight by his prized Pikachu.
Pikachu manages to rally and pull off the most unlikely of upsets by forcing a double knockout, but as Ash has no more Pokémon remaining, Tobias still emerges victorious, with the rest of his party forever remaining a mystery.
2 Tobias' Dakrai Immediately Cuts Ash's Team In Half
After Ash's grueling battle with Paul in the previous round at the Lily of the Valley Conference in Sinnoh, Ash is full of confidence going into his semi-final bout against Tobias, but this confidence is immediately replaced with desperation and anxiety when Tobias sends out Darkrai and it begins to sweep through Ash's team.
Darkrai is a formidable Mythical Pokémon, and while it makes quick work of Ash's Heracross, Torkoal, and Gible without much resistance, it makes Ash's Sceptile look even better when it finally manages to get past the dangerous Dark-type Pokémon.
1 Alain's Charizard Is Too Much For Ash-Greninja
Even though Ash eventually manages to get his Pokémon League win in Alola, many fans still believe that he should have won the Lumiose Conference in Kalos. His Kalos campaign sees him amass perhaps his best-ever team and overcome several tough hurdles on his way to the final, with Kalos being a region full of Mega Evolution.
Alain's Charizard ends up being the final hurdle that Ash fails to get past, but it is not too much of a shock, considering how strong Alain's ace is made to look in the anime. It easily defeats Trevor's own Mega Charizard in a previous round, and is able to deal with Ash's special connection with Greninja and earn Alain the league victory.