Ash Ketchum owns a lot of Pokemon. Certain Pokemon are always going to stand out more than others, whether it's for being really good at battling or... really not good at battling. That said, some in that bunch get undeservedly lost in the shuffle.
The Charizards, Sceptiles, and Lucarios on his roster have gotten enough attention. This list aims to shine a light on Ash's more underrated Pokemon, those that have performed admirably in important battles and yet aren't talked about as some of his best.
10 Heracross
Heracross might as well have been Ash's best Johto Pokemon, and yet no one really puts it in the conversation as one of Ash's best. With what's been shown so far, you could reasonably put Heracross up against most of Ash's Pokemon and expect it to win.
It's had excellent showings against Pokemon with type advantages against it, such as Rochelle's Donphan, Shingo's Scizor, and Gary's Magmar. It's also appeared and pulled its weight in some of Ash's biggest battles, including the aforementioned battle against Gary at the Silver Conference, and against Nando and Tobias at the Lily of the Valley Conference.
9 Kingler
Not many will remember it as one of Ash's strongest, but Kingler actually has one of the best battling records among any of Ash's Pokemon. Its first and most involved battle was an impressive one, too, single-handedly wiping out three out of three opposing Pokemon during the first round of the Indigo League. Not many Pokemon on Ash's roster can claim they've performed that feat.
Unfortunately, Kingler hasn't been used much since, only getting two more knockouts on fellow Water-types: a Cloyster at the Indigo League and a Poliwhirl at the Whirl Cup. Still, its Crabhammer is no joke, being arguably its main weapon for finishing off opponents.
8 Glalie
Glalie wasn't used often, having been caught late into Ash's Hoenn journey, but the few battles he's been in have shown quite a bit of skill. Even as a Snorunt, he proved to be quick on his feet and spontaneous enough to deal with Ash's unpredictable battling style.
His power multiplied quite a bit after he evolved and he showed that power in all its glory during Ash's run through the Hoenn League. He notched some impressive knockouts against several Pokemon, including a few he had type disadvantages against, namely Clark's Charizard and Morrison's Metang. While his best attack was Ice Beam, he could get also physical, packing a pretty strong Headbutt.
7 Swellow
Ash's regional bird roster is a saturated flock, and with Pidgeot and Staraptor being as popular as they were, and Unfezant being as disappointing as it was, Swellow is often forgotten about, despite arguably being the best of that bunch.
Ash's first Hoenn capture deserves credit for being one of the grittiest Pokemon on the roster, consistently taking a lot of damage despite not having a tanky build. It has several strong wins, too, from the intense one-on-one against Winona's shiny Swellow, to the infamous "Thunder armor" moment against Tate and Liza, to some key knockouts against Battle Frontier Brains Tucker and Spenser.
6 Bayleef
Bayleef is much more known for her obvious affection towards her Trainer, though that overshadows her more-than-solid abilities on a battlefield. She doesn't have as many battles under her belt as others, but the few she's participated in prove her skill, especially after evolving from a Chikorita.
She came up huge against Fighting-type Gym Leader Chuck, beating both of his comparatively bulkier Pokemon single-handedly after Pikachu got knocked out early. She was also an important member of the team during Ash's run through the Johto League, pulling her weight with a win against Harrison's Houndoom and dealing some damage against Gary's Blastoise and Harrison's Blaziken.
5 Quilava
Fellow Johto starter Quilava is no slouch either. While the best version of itself is yet to come having evolved pretty late, it already had quite a few shining moments as a Cyndaquil.
It was a Gym battle regular during Ash's Johto cycle, having participated and gotten a few good knockouts against Bugsy, Whitney, Morty, Jasmine, and Pryce. While it didn't do much in the Silver Conference, it made up for it with its first official battle as a Quilava, getting a neck-and-neck draw against Nando's Armaldo at Sinnoh's Lily of the Valley Conference. Not to mention, it blasted off a gigantic Team Rocket mecha with Eruption the day before.
4 Buizel
Right after the trade that sent him from Dawn's team to Ash's, Buizel had quite a few memorable showings in Gym battles, knocking out Maylene's Lucario in a down-to-the-wire draw, and later defeating its own evolution: Crasher Wake's Floatzel. He was also a key contributor in Ash's rematch against Paul at the Sinnoh League, knocking out a Gastrodon and dealing solid damage against Drapion.
More than his actual battling record, though, Buizel deserves credit for executing a lot of the out-of-the-box tactics that would later shape Ash's battling style. His so-called Ice Aqua Jet and Counter Shield schemes were quite effective and heavily relied upon in several matches.
3 Corphish
While many will remember Corphish as a comic relief Pokemon, it was arguably Ash's best workhorse through his Hoenn travels. A lot of high-stake battles have his fingerprints (or...clawprints?) on them, and usually for the better.
Corphish racked up knockouts in its Gym battles against Brawly and Juan, and came up big against the type-disadvantaged Flannery. It did even more work in the Hoenn League, participating in four matches total and helping Ash reach the top eight. Finally, it did some work during Ash's Battle Frontier gauntlet, teaming up with Swellow to defeat Tucker's Swampert and Arcanine, and appearing in both his matches against Anabel.
2 Dracovish
The newest member of the Journeys rotation is already making its mark in what may be the most important battles of Ash's life. For all the attention Lucario, Gengar, and Dragonite may get, Dracovish was the one that got Ash out of a lot of potential World Coronation Series losses.
Basically, all of its wins were either important come-from-behind knockouts or match-winning knockouts. All came against incredibly strong opponents, too; Iris's Dragonite, Clemont's Diggersby, and Drasna's Noivern were all victims of Dracovish's unexpected power. Despite being a Water/Dragon-type, its Ice Fang has been a key weapon against fellow Dragon-types.
1 Bulbasaur
Thanks to Ash's roster being pretty saturated with starters, Bulbasaur doesn't quite get the attention, even though it's far from being the worst in battle. In fact, among the Grass-type starters, it's arguably the second or third best behind Sceptile and (maybe) Rowlet.
The proof is in its battling resume, having participated in a lot of key matches. No matter the opponent, whether it was a budding Trainer in the first round of a League, or a Frontier Brain with a Legendary Titan, it's proven to be remarkably consistent, always relied upon as a fall-back option to get key knockouts in come-from-behind situations.