Summary

• Alder never loses a real battle, appearing undefeated on-screen despite an unconventional "defeat" to Ash.
• Alder's true battling talent is displayed in a real battle against Trip, easily defeating his Serperior.
• Despite his apparent retirement, Alder remains the only Pokémon Champion undefeated in proper battles in the anime series.

Pokémon's Leon has a reputation for being undefeated, or at least he did until he lost to Ash in the climactic round of the Masters' Eight Tournament. However, there's still one champion who has never been defeated on screen in a proper battle, and he didn't even make it to the Masters' Eight at all: Alder.

Alder was the Champion of the Unova region during Pokémon Black & White who only appeared on a handful of occasions. By the time of Journeys, it seems Alder has retired, as Iris has taken his place as Unova's Champion for the Masters' Eight. Alder was established as being experienced, and seemed to have been the Champion for quite a long time when he met Ash. However, he was also introduced flirting (unsuccessfully) with Officer Jenny, nearly getting arrested in the process.

In "Ash Versus the Champion!", Alder goes on to have a battle with Ash, only things don't quite go according to plan.

Alder Never Loses a Real Battle, But...

Alder calls out his Bouffalant, which takes several attacks from Pikachu without flinching. In fact, Alder doesn't even react at all--he's actually fallen asleep mid-battle, prompting his own Pokémon to turn on him. Bouffalant rams into Alder, knocking him into a tree, and Alder gives up, even though Bouffalant is perfectly capable of battling. While Alder technically concedes to Ash, it's clear that this wasn't a real contest in any way, and that Alder wasn't taking Ash seriously as an opponent.

Alder has only one other battle that is shown in the series. In "Jostling for the Junior Cup!", Alder is present at the Pokémon World Tournament Junior Cup to have an exhibition battle with the winner of the cup, which turns out to be Ash's rival, Trip. Here, in a real battle, Alder actually pays attention, and using that same Bouffalant, is able to easily defeat Trip's Serperior without breaking a sweat. This is the only taste fans get of Alder's actual battling talent.

Whether one wants to count Alder's "loss" to Ash or not, Alder's single real battle proves that he was worthy of the title of Champion, even if his general behavior might indicate otherwise. Interestingly, there is no indication as to whether Iris ever battled Alder for the title of Champion; it has been shown, by characters like Cynthia, that a Champion can retire without losing to someone else, simply vacating the spot. Given Alder's age, it seems quite possible that he retired without battling Iris to keep his title at all.

While Alder is easily the least impressive Champion seen in the series, he does bear the distinction of winning his only real on-screen battle, making him technically undefeated--although there's a big asterisk next to that one. Since every other Champion known in the anime participated in the Masters' Eight Tournament, and thus lost at some point on screen, that leaves Alder as the only one who's never suffered a legitimate defeat in the Pokémon anime.