The gym leaders of the Pokémon world are some of the most formidable trainers in the series. They’re the end of level bosses, essentially, to be defeated in sequence to allow the player passage from the beginning of a given game to the final challenge at the end.

Whether they actually earn their fearsome canonical reputation is a different matter, though. AI trainers can be super tough, but they’re still AI trainers, liable to choose the wrong moves on a given turn and often reliant on the questionable level-up movesets of their critters. Gym Leader/Elite 4 member and Poison-type expert Koga has used a wide variety of Pokémon across the games, but which were his best and which were his worst?

10 BEST: Muk (Johto Gym Leader Castle, Pokémon Stadium 2)

Naturally, one of Koga’s better Pokémon would be one of the iconic and dangerous Poison-types of Generation I. When it comes to viability, movesets are just as important as the Pokémon choice itself, and the Muk Koga used in the first round of the Johto Hym Leader Castle in Pokémon Stadium 2’s Elite 4 was not messing around at all.

It could be anywhere from level 50 to 100 (as with the rest of his team) and sported a moveset of Sludge Bomb, Toxic, Fire Blast, and Double Team. This gave it strong STAB, one of the most deadly status moves in the game, a powerful attack to use against Steel-types (which are immune to Poison) and the ever-infuriating hax chance of Double Team. The Burnt Berry it held may need replacing, but otherwise, this is a viable competitive set.

9 WORST: Koffing (Pokémon Red & Blue Gym Battle)

From a non-competitive point of view, the worst Pokémon can sometimes be simply considered the lowest-level one. Which is the lowest Koga has ever wielded in the games? A level 37 Koffing.

While the Kanto region was home to some mighty ‘mon, pickings were very slim when it came to Poison Pokémon. Not quite as slim as for Ghost- and Dragon-types (which were represented by just the Gastly and Dratini evolution lines respectively), but slim. As a result, Koga’s team consisted of two Koffings, a Weezing, and a Muk in the original game. Koffing #1 and Koffing #2 were both level 37, with movesets of Sludge, Smog, Tackle, and Smokescreen.

8 BEST: Venomoth (Pokémon: Let’s Go! Gym Battle)

With the launch of Pokémon: Let’s Go Pikachu & Eevee, Game Freak took the opportunity to spruce up Koga’s team a little. Well, a heck of a lot. His Pokémon Yellow team was very lackluster (as seen in the next entry), but he was quite a threat here.

His ace is a level 44 Venomoth. This beastly creature packs a moveset of Bug Buzz, Sludge Bomb, Psychic, and Protect. While the latter may not be particularly useful in this context, That’s a solid special attacking set with the best dual STAB options Venomoth can really muster.

7 WORST: Venonat (Pokémon Yellow Gym Battle)

So, yes. Koga’s Venomoth is more than capable of ending foolhardy challengers’ entire battling careers (or at least send them scurrying back to a Pokémon Center). It’s great to see that he’s learned his lesson, as in the original Pokémon Yellow, he didn’t bother evolving most of them!

His team in Yellow really wasn’t up to snuff, boasting three Venonats and a Venomoth. None of them had any STAB moves (Toxic doesn’t count of course) beyond Venomoth’s Leech Life, which was super weak before its recent base power buff. The weakest of these Venonat was level 44.

6 BEST: Toxicroak (Pokémon HeartGold And SoulSilver Elite Four Rematch Battle)

On his ascension to the level of an Elite Four member for Generation II, Koga was surely expected to bring a lot of new firepower to the table. He certainly managed this in Pokémon HeartGold and SoulSilver, especially in his rematch battle.

In this new match, he makes changes to his Elite Four team, adding a Toxicroak to the mix. At level 60, it’s –just slightly— the lowest levelled member of his team, but it’s a fantastic asset. With Gunk Shot, Cross Chop, X-Scissor, and Swagger, it packs a mighty punch.

5 WORST: Ariados (Pokémon Gold, Silver, And Crystal Elite 4 Battle)

Meanwhile, back in Pokémon Gold, Silver, & Crystal, Koga’s Elite Four team was lacking a certain punch. The weakest link, perhaps, was a Pokémon that has historically been very underwhelming: Ariados.

The one he used in this battle was level 40 and had a less-than-stellar moveset of Spider Web, Giga Drain, Baton Pass, and Double Team. This rendered the battling bug (far removed from the strongest specimens that the Bug-type has to offer) little more than an annoyance. At least Koga gave it Poison Jab in HeartGold & SoulSilver, for some kind of potent STAB.

4 BEST: Weezing (Pokémon Let’s Go! Gym Battle Rematch)

Weezing is another iconic Poison-type that Koga was probably contractually obliged to use. It’s also appeared in several of his teams, but the best Weezing he used features in the rematch against him in Pokémon: Let’s Go!

It’s level 56 and is armed with Sludge Bomb, Fire Blast, Thunder, and Toxic. Weezing isn’t the most powerful special attacker around, but the high base power of these moves can make this offensive set more of a threat than overconfident players may expect.

3 WORST: Muk (Pokémon HeartGold & SoulSilver Elite Four Rematch)

Generally speaking, rematches against Pokémon trainers are intended to be more difficult. This particular Muk of Koga’s didn’t seem to get that memo, however.

There are a lot of mighty Poison moves in the series, but Koga saw fit to give this Muk only status moves. Toxic, Screech, Swagger, and Minimize really isn’t going to get this unfortunate critter anywhere. Its Black Sludge was a solid pick, but this annoying non-set is a bit of a disaster otherwise. It’s a shame, considering the other Muk of Koga’s that kicked off this list.

2 BEST: Tentacruel (Pokémon Let’s Go! Gym Battle Rematch)

Statistically, Tentacruel is a solid Kanto Pokémon that has been given some handy new moves since its introduction (Scald, Toxic Spikes, and so on). can thrive in an offensive or defensive role. Koga doesn’t make very much use of it, but it is a core part of his team for the rematch battle in Let’s Go!

Its moveset of Hydro Pump, Sludge Bomb, Mega Drain, and Toxic isn’t bad at all (though Mega Drain really should be replaced). Players who run Tentacruel as more of a special attacker, utilizing its surprising Speed and the Poison-type Dynamax move to accrue very welcome buffs, will appreciate this set.

1 WORST: Forretress (Pokémon Gold, Silver, & Crystal Elite Four Battle/HeartGold & SoulSilver Elite Four Battle)

Well, strike one here is the fact that Forretress isn’t a Poison-type. Koga does have a secondary preference for Bug-types, so this isn’t too much of an issue. The real problem here is that Forretress is super passive by nature.

The Forretress Koga went on to use in the Elite Four battle in Pokémon HeartGold & SoulSilver is all but identical to the one he uses in Gold, Silver & Crystal, with just one difference: the former uses Toxic Spikes and the latter has Spikes. Their other three moves are Protect, Explosion, and Swift, making this Pokémon, in both instances, a huge waste of a party slot in a match as high stakes as an Elite Four battle.

NEXT: Pokémon: Every Poison-Type Gym Leader, Ranked According To Difficulty