In case you missed all the obvious signs, the trainers here primarily use Grass-type Pokémon. When you enter, speak to the Ball Guy on the right. You'll receive a Friend Ball. Keep this for an extra-special Pokémon because it's extremely rare. If you reckon you're up for it, speak to the Gym staff in the centre to begin the Gym mission.
Know Your Match-Ups: Grass
Grass-type Pokémon have many weaknesses: Fire, Ice, Flying, Bug and Poison. Meanwhile they're strong against Water, Ground and Rock-types and they resist Water, Grass, Electric and Ground moves.
Scorbunny users should have an extremely easy time. Otherwise, you'll probably want to rely on Fire, Flying or Bug-type Pokémon that you've caught. Rookidee can be found as early as Route 1, while you grab Vulpix or Growlithe from Route 3.
A Blazing Victory
If you're feeling brave, there's a really easy way to demolish this Gym. Firstly, you want to catch a Vulpix or Growlithe from the Wild Area or Route 3. Next, enter the Wild Area from the Motostoke side. So you should be in East Lake Axewell. With Motostoke as north, head east, then cross the bridge north into Motostoke Riverbank.
As soon as you leave the bridge, turn left and head towards the wall in the faraway distance. Be wary of all the strong Pokémon about; use a Poké Doll to escape if necessary. There should be a tree in the distance and item capsule towards the right, containing a Fire Stone. Use this evolve your Vulpix/Growlithe, then speak to the café owner in any Pokémon Centre to relearn a bunch of powerful moves!
The Gym Challenge
In each Gym, you'll need to complete a Gym mission first. This usually involves some kind of puzzle, with trainer battles scattered throughout. After clearing the Gym mission, you can enter the inside of the stadium to battle the "boss" of the Gym: the Gym Leader. Succeed and you'll acquire one of the eight Gym badges.
The Gym mission here is a rather unique one: you'll play the role of shepherd, as you try to herd a bunch Wooloo towards a goal line. There are 20 Wooloo in the Gym and all 20 must go past the goal line. Wooloo will try to move away from you. So bear that in mind as you move. Also, they will run away from any Yamper that they see.
In front of you, there will be 13 Wooloo all huddled up. Above these, there are 3 more Wooloo on the right, then 4 more Wooloo on the left. The goal line is directly north and there are no obstructions in the way, so it should be an easy task. What you can do is approach the first bunch of Wooloo from their bottom-left corner. So walk a bit left from the entrance, before going up.
The Wooloo should roll away towards the north-east, where the next 4 Wooloo are. Once these groups have combined, move yourself more to the right so that the Wooloo turn towards the north-west. That way, they'll combine with the final group. After that, move yourself more to the left. If done correctly, all 20 Wooloo should roll comfortably through the goal line.
If there are any stragglers, go back and collect them. There's no time limit and the Wooloo won't move if you aren't nearby, so there's no need to rush. In the second area, there's a Yamper running around in a wide ellipse. It will scare the Wooloo and make them roll towards the left. Wait until the Yamper is far away, then drive the Wooloo north into the next goal area.
Before you can continue, there's a trainer standing between the two areas.
Gym Trainer Samuel
A pure Grass-type that can be found on Route 3. We shouldn't need to tell you what Pokémon to send out!
In the third area, there are two hedges along the centre, going from top to bottom, creating three paths. A Yamper will be running clock-wise around the left-hand side hedges. Meanwhile, there's a Gym trainer waiting between the right-hand side hedges and the wall. Essentially, you have to choose between risking an encounter with Yamper or fighting the trainer.
If taking the Yamper route, you'll want to go along the left-most path. Start pushing the Wooloo up this path as Yamper is halfway along its northbound path. That way, you'll be traveling up while Yamper is going down the middle path. Or you could just fight the trainer for the glory!
Gym Trainer Mark
Budew and Oddish are both Grass and Poison-types. That means they're weak to Fire, Ice, Flying and Psychic.
The fourth and final area is slightly more complicated-looking. In the very centre, there are two small rows of hedges, like an "equal" sign. On the left and right side are a singular line of hedges, both patrolled by a Yamper running anti-clockwise. Above all of these hedges is a Gym trainer looking left and right. If you want to avoid everything, you've got to be smart.
The ideal route is via the path furthest to the right. You want to use the same logic to avoid the Yamper like last time. Wait till the Yamper is halfway along the path on the left of the hedge, then squeeze those Wooloo through the path on the right. If you reasonably close to the right, you'll also avoid the gaze of the Gym trainer. Win-win!
Gym Trainer Leah
There's nothing here that should tax your brain. Bounsweet is a pure Grass-type and we already went through the weaknesses of Grass and Poison-types for the previous trainer.
Bring all of the Wooloo to the fourth goal area and the path ahead will open. Keep going north, up the stairs to the exit. You'll be taken inside the stadium. When you're ready, proceed through the entrance tunnel towards the stadium grounds. There, you'll come face to face with Milo once again, but this time as opponents.
Gym Leader Milo
Milo starts off easy with Gossifleur. If you've yet to encounter one, it's a pure Grass-type. That means it's weak to Fire, Flying, Ice, Bug and Poison. His second and final Pokémon is Eldegoss, which is an evolved Gossifleur. It has stronger stats, but is still a pure Grass-type. So countering it should be easy. That said, be careful as Milo will Dynamax it ASAP.
In certain places like Gym Stadiums and Max Raid Battles, you will able to Dynamax your Pokémon. Simply press the big "Dynamax" button to the left of your Pokémon's moves. This will change all of your moves into "Max Moves". Choose one and your Pokémon will Dynamax on their next turn, becoming much larger than normal. Dynamaxing lasts for 3 turns.
While Dynamaxed, your Pokémon will have increased HP. Also, they can use Max Moves, which are extremely powerful and can confer a variety of special effects. For example, all Fire-type moves become Max Flare, which changes the weather to be sunny, boosting the power of Fire moves. The power of a Max Move depends on the move it replaced.
A Dynamaxed opponent is pretty scary, so we recommend Dynaxming your own Pokémon during the turn Milo sends out Eldegoss. In fact, if you're confident you can beat Gossifleur and Dynamxed Eldegoss within 3 turns, you could Dynamax as soon as the battle begins.
Mow down Milo's Grass-types and you'll receive the Grass Badge from him. Afterwards, he'll also give you TM10 Magical Leaf and a replica Grass Uniform. From here, your next destination is Hulbury, where the 2nd Gym--the Water Gym--is located.
As soon as you can, exit the Gym, then head east from the Pokémon Centre to get to Route 5.
Gym Badge Upgrade
As you collect Gym Badges, the Level of Pokémon that obey you and the Level of Pokémon that you can catch will steadily increase. You can check out this information by viewing your League Card. Additionally, the variety of items you can purchase from the Poké Mart will increase.