Gym Leader Level: 41–42
Path to Montenevera
Getting to Montenevera can be a little bit tricky, as you’ll need to climb some of Glaseado Mountain, and unless you have the ability to climb with your Koraidon/Miraidon (which isn’t likely if you’re doing things in order), it can be a bit of a pain. Thankfully the map up above should help, but following the directions below is also a good idea, as it can be a bit hard to see the path in the snowy mountainside.
From Medali, take the northeast road (not the one leading to a cave in Glaseado Mountain) and follow it until you cross a bridge. Take a right to follow the Glaseado Mountain Path, and then follow that path until you reach another fork in the road. From there, take the eastern path, climb the hill into the snowy mountain, and keep going until you find the Pokémon Center.
From the Pokémon Center, head east, along the relatively smooth slope, and keep your eye out for Trainers and signposts. There aren’t any visible paths or roads, so keep that in mind.
When you reach what appears to be a dead end from the smooth slope, with a rather large ice hill, you’re going to want to turn 180° and climb the path up the mountain. You should hopefully see a Trainer up that path, and if you do, you’re right near the entrance to Montenevera.
Montenevera
Montenevera itself is fairly quaint, although it is spread out a bit. The Pokémon Center is near the entrance, so you’ll need to follow the steps towards the Gym in the southeastern end of town.
It’s also a good idea to remember that there’s an NPC near the Pokémon Center that you can give Bottle Caps or Gold Bottle Caps for Hyper Training your Pokémon, and you can buy Bottle Caps for 
20,000 each in Delibird Presents shops throughout Paldea.
You can find a Covert Cloak at the base of a tree to the west of the Pokémon Center. There’s a Dusk Stone behind the Gym, which can be used to evolve Misdreavus into Mismagius or Murkrow into Honchkrow. There’s TM136 Electric Terrain up a hill west of the Gym, but it will require high jumping and some maneuvering to get to if you lack the ability to climb walls.
If the Montenevera Gym is the sixth Gym you’re taking on (so you have five badges already), you’ll find Jacq waiting for you inside, and he’ll give you the Lucky Egg item, which boosts the amount of Exp. Points the holder earns after battle and is very useful for training or for helping new additions catch up. If you’re taking on Montenevera Gym out of order, that’s fine, too, you’ll just get the Lucky Egg from Jacq in a different Gym after you’ve earned five Badges.
Montenevera Gym
The Gym Test is fairly straightforward: you’ll need to build hype for the Gym Leader battle by going out on a music stage and fighting three challengers in a row. Unlike all of the other battles so far, you’ll have to fight these Trainers in a Double Battle, meaning both sides will use two Pokémon simultaneously. You’ll also occasionally receive cheers from the crowd in the battles that can affect your stats temporarily.
The first challenger uses a Greavard Lv. 40 and a Shuppet Lv. 40; the second challenger uses a Misdreavus Lv. 40 and a Haunter Lv. 40; and the final challenger uses a Drifblim Lv. 40 and a Sableye Lv. 40.
After beating the three Trainers, you can return to the receptionist at the Gym and challenge the Gym Leader, Ryme. As with the previous fights leading up to her, you’ll have to fight her in a Double Battle as well, so plan accordingly. You also may receive cheers from the crowd during this fight, too, hopefully making it a bit easier for you.
Gym Leader Ryme
7,560
Icy Wind
Sucker Punch
Shadow Sneak
Light Screen
Slash-
Shadow Sneak
-
Crunch
-
Phantom Force
Play Rough
-
Hyper Voice
Discharge-
Hex
Ryme specializes in Ghost-type Pokémon and is also the only Gym Leader you’ll have to fight in a Double Battle, so you’ll have to take on two of her Pokémon at once. Normal-type Pokémon (but not moves!) are generally a good option here, as are Dark-type Pokémon or moves. You can also use your own Ghost-type Pokémon or, better yet, Ghost-type moves against her as well.
Throughout the battle, your Pokémon may receive random cheers from the crowd, which will raise their stats. This can help give you an edge in battle.
She leads with her Banette and Mimikyu at the same time. Mimikyu has Disguise for its Ability, meaning you will have to hit it with a damaging move first in order to break the disguise, acting sort of like a Substitute in the sense that you cannot affect it with Status moves. Because of this, unless you have a move that strikes twice in one turn, it will take at least two attacks to take Mimikyu down.
Banette has Icy Wind, which hits both of your Pokémon and also lowers their Speed by one stage. It has Sucker Punch to hit anything first, so long as it is using an attacking move, and then it has Shadow Sneak for a priority move.
Mimikyu has Light Screen, which reduces the damage of your Special-based moves for the next five turns, so it can be a bit unfortunate if it sets it up and you depend on those moves. You might be able to take out Mimikyu in two hits if you have both of your Pokémon target it, so consider that if you primarily use Special-based moves, otherwise you may have to wait out the turn timer for it to wear off or deal with doing much less damage. It also has Shadow Sneak and Slash for moves.
Next up is her Houndstone, which has some rather nasty moves: Play Rough, Crunch, and Phantom Force. Phantom Force is annoying because it will vanish for a turn, meaning anything targeting it will fail until it returns. Play Rough also counters Dark-type Pokémon.
Lastly, she’ll send out her Toxtricity. This Toxtricity will Terastallize on the first turn into a pure-Ghost-type, so don’t consider its usual Poison/Electric typing when choosing a move to use against it. It has Discharge, Hex, and Hyper Voice for moves. Discharge will hit all other Pokémon, including its ally, and has a chance of paralyzing it; Hex is particularly worrisome if you become paralyzed, as it will do double the usual damage and hit quite hard; and lastly, Hyper Voice hits both Pokémon on your side of the field.
After you’ve beaten her, she’ll give you a badge and TM114 Shadow Ball.
Where to Go Next
If you’re following the Victory Road storyline, you’ll want to head all the way to the southwest part of Paldea, going through a rather large cave or taking a bit of a detour if you can’t jump high, in order to get to Alfornada. If you’re following the recommended order, you can either go there or you can return to the Asado Desert to take on the Quaking Earth Titan—they’re both at the same level, 45, but the Quaking Earth Titan is a little easier.