Location: Hau'oli City

Your first encounter with Team Skull is in Hau'oli City. When you go to the Shopping to find Ilima, the Trial Captain, you will be accosted by two Team Skull Grunts who want to take the Pokémon from Ilima. Ilima stands firm in his refusal and you battle the grunt, with Hau complaining at how they tear down Totem Stickers. They leave saying nobody needs to know about their failure.

Location: Big Wave Beach

As you travel through Route 2, you will get ushered into the Big Wave Beach. When there, you will find Team Skull are harassing one of the Mantine used for Mantine Surf. You need to defeat them.

Location: Verdant Cavern

During the first Island Trial, the two Team Skull grunts will interrupt as revenge for you getting in their way. They will once again challenge you. Once defeated, however, they will then block various holes where Gumshoos/Raticate will come out of, trying to sabotage your trial.

Location: Paniola Town

As you go through Paniola Town, you will see several Team Skull grunts attacking a Vulpix. Vulpix is holding onto a Bottle Cap and the grunts want the Vulpix to give it to them. Once again, you need to defeat them.

Location: Route 5

The next encounter with Team Skull is on Akala Island with a different pair of grunts. These grunts don't battle you but do in fact speak to Gladion, who they yell at for stopping them from stealing the Totem Pokémon. They mention how despite their boss liking Gladion, he will never be a member of Team Skull.

Location: Route 6

When on Route 6, approaching the Royal Avenue, you will see two Team Skull grunts harassing a trainer with Mudsdale and Drifloon. It appears the grunts are the same ones you dealt with on Melemele Island, and their defeat caused them to be exiled to Akala Island. Here, they are trying to take a Drifloon. The trainer introduces herself as Hapu and requests your help in dispatching the Grunts.

Location: Diglett's Tunnel

When travelling through the Diglett's Tunnel, you will encounter two employees who will greet you. They will inform you that Team Skull had been riling up Pokémon in the area and that Team Skull often interfere with Pokémon. Soon after, you and Hau will meet two Grunts who quickly challenge you to a battle

Location: Memorial Hill

As you get to Memorial Hill, you will encounter two Aether Foundation employees battling with two Team Skull grunts. The Aether Foundation employees request your help in dealing with Team Skull so you battle the grunts. After that, you soon meet Plumeria who mentions that Gladion mentioned you. She says about how she's like a big sister who keeps Team Skull together and challenges you for picking on her brothers and sisters.

Team Skull Admin Plumeria	Golbat	Salandit
Battle Type Items	Level 26	Level 27
	Attacks: Poison Fang Wing Attack Confuse Ray	Attacks: Flame Burst Dragon Rage Poison Gas
	Hold Item: No Item	Hold Item: No Item

Location: Route 10

The next encounter with Team Skull is a very minor encounter in Route 10 where you confront the two grunts waiting for a bus. Defeat them and they mention returning to living large in the mansion.

Location: Malie Garden

When you go to Malie Garden, you will see Kukui facing off against two grunts. When you go to help him, someone interrupts. They introduce themself as Guzma, the leader of Team Skull. Guzma has history with Kukui, stating how they were both rejected to being Trial Captains and that the League he's building is irrelevant as everyone knows he's the strongest trainer in Alola. He spots you and your Z-Ring and questions you as to why you bother with it. He then decides to challenge you to destroy things that Kukui loves

Team Skull Boss Guzma	Golisopod	Masquerain
Battle Type Items	Level 34	Level 34
	Attacks: Sucker Punch Razor Shell First Impression	Attacks: Air Slash Bug Buzz Icy Wind
	Hold Item: No Item	Hold Item: No Item

Location: Route 15

The next encounter with Team Skull is a brief one. As you approach the Aether House, a Team Skull grunt will question Lillie about what's in the bag, since it was moving. You'll battle him and then he'll then quickly run off.

Location: Route 15

After completing Acerola's trial, when you return to the Aether House, you will interrupt Plumeria and two Skull Grunts who weren't expecting you back so soon. They quickly challenge you.

Team Skull Admin Plumeria	Golbat	Salazzle
Battle Type Items	Level 37	Level 38
	Attacks: Wing Attack Poison Fang	Attacks: Dragon Pulse Flamethrower Sludge Bomb
	Hold Item: No Item	Hold Item: No Item

After defeating, you then learn that Team Skull stole a child's Yungoos as a message for you to come alone without backup to their base in Po Town to meet their boss.

Location: Route 17

The next encounter with Team Skull is in Route 17. As you are trying to go to Po Town, they then accuse you of coming to mock them because they never were able to complete the Island Challenge. Defeat all the grunts in Route 17 and they will leave, without you being able to get in. Then, a mysterious man will appear and let you in.

Location: Po Town

Po Town is a unique town in that it has been completely overrun by Team Skull. There's grafitti everywhere and they even have control of the Pokémon Center, where they will charge you to heal your Pokémon. You need to navigate various paths to get through Po Town, defeating grunts along the way, in order to make it to the Shady House in the back.

Location: Shady House

In the Shady House, you need to make it up to Guzma's room. To do so, you have to find three passwords scattered across the house. One is Golisopod, another is Tapu Cocoa and the other is Beat Up. You also need to say "No" when asked if you are sure about the passwords. Defeat all the grunts along the way. When you get to Guzma's room, he yells at you to just care about your Pokémon and stay out of his business. He then challenges you.

Team Skull Boss Guzma	Golisopod	Masquerain	Pinsir
Battle Type Items	Level 41	Level 41	Level 41
	Attacks: Sucker Punch Razor Shell First Impression	Attacks: Air Slash Bug Buzz Icy Wind	Attacks: Throat Chop Storm Throw X-Scissor
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item

Defeat him and you'll get the Buginium Z and he'll order his underlings to give Yungoos back. They then mostly evacuate Po Town. However, you quickly learn that this was a distraction and that Plumeria and some grunts have kidnapped Lillie. Gladion suggests going to the Aether Paradise.

Location: Aether Paradise

In the Aether Paradise, as you battle through the Aether employees, when you come to the end you will find that Team Skull has been working with the Aether Foundation to hunt for the Pokémon that Lillie stole, Cosmog. You need to battle through the grunts after Gladion rushes through to attack Guzma. With Guzma having defeated Gladion and chastising him for failing, with him saying how he crushed Gladion, you then have to face Guzma yourself.

Team Skull Boss Guzma	Golisopod	Masquerain	Pinsir	Vikavolt
Battle Type Items	Level 45	Level 45	Level 45	Level 45
	Attacks: Sucker Punch Razor Shell First Impression	Attacks: Air Slash Bug Buzz Icy Wind	Attacks: Throat Chop Storm Throw X-Scissor Stone Edge	Attacks: Flash Cannon Thunderbolt Bug Buzz Energy Ball
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item

Defeat him and he will eventually join you up when you're trying to stop Lusamine, however when Lusamine goes into the Ultra Wormhole, Guzma follows her in.

Location: Ancient Poni Path

As you go through Poni Island in an attempt to revive Solgaleo/Lunala and retrieve Lusamine & Guzma, you get stopped by a group of grunts who challenge you. Defeat them and Plumeria will appear. She asks if you're really able to get Guzma back, and then apologies for what she did to Lillie, giving you the Poisonium Z.

Location: Altar of the Sunne/Moone

As you reach the Altar of the Sunne/Altar of the Moone, you will notice Guzma getting thrown out of the Ultra Wormhole with Lusamine. After the Necrozma incident, he will start to realise that he has perhaps gone about things wrong.

Location: Route 15

During Mina's Trial, you will encounter Guzma by the Aether House. He will seem very apologetic over what happened and thank you for your help. Hau will ask him about his Golisopod and he'll say how it has been with him since before he did his Island Challenge and that he really likes his team. He will then give you a Grip Claw

Location: Vast Poni Canyon, Route 13, Po Town

Team Skull still has a presence across the Alola Region after completing the game. They will still be in Po Town, though the grunts in the Pokémon Center will sell you a special Team Skull tanktop. Guzma & Plumeria can also be found out of Team Skull clothing and in regular clothing in Route 13, with other former Team Skull Grunts.

Location: Team Rocket's Castle

During the takeover of the Aether Paradise by Team Rainbow Rocket, Guzma will rush up to Aether Paradise worried about Lusamine. With something he cared about being taken by Team Rainbow Rocket, he will assist you in taking out grunts and finding the way to save Lusamine. He will even battle in a Multi-Battle against Team Rainbow Rocket

Pokémon Trainer Guzma	Golisopod	Vikavolt	Pinsir	Masquerain	Scizor
Battle Type Items	Level 64	Level 64	Level 64	Level 64	Level 64
	Attacks: Sucker Punch Waterfall First Impression Brick Break	Attacks: Flash Cannon Thunderbolt Bug Buzz Energy Ball	Attacks: Throat Chop Storm Throw X-Scissor Stone Edge	Attacks: Air Slash Bug Buzz Ice Beam Energy Ball	Attacks: X-Scissor Iron Head Night Slash Bullet Punch
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item

Details:
Having disbanded Team Skull, Guzma has come up to the league to show that he is a strong trainer.

Pokémon Trainer Guzma	Golisopod	Vikavolt	Pinsir	Masquerain	Scizor
Battle Type Items	Level 68	Level 68	Level 68	Level 68	Level 68
	Attacks: Sucker Punch Waterfall First Impression Brick Break	Attacks: Flash Cannon Thunderbolt Bug Buzz Energy Ball	Attacks: Throat Chop Storm Throw X-Scissor Stone Edge	Attacks: Air Slash Bug Buzz Ice Beam Energy Ball	Attacks: X-Scissor Iron Head Night Slash Bullet Punch
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item

No longer a part of Team Skull, Plumeria will mention about how Nanu suggested she come to the League to test the strength. Having obtained a Z-Power Ring, she poses a threat with Poison-type Pokémon..

Pokémon Trainer Plumeria	Gengar	Muk	Crobat	Toxapex	Salazzle
Battle Type Items	Level 67	Level 67	Level 67	Level 67	Level 67
	Attacks: Shadow Ball Dark Pulse Sludge Bomb Dazzling Gleam	Attacks: Venoshock Brick Break Toxic Rock Slide	Attacks: Leech Life Fly Poison Fang Protect	Attacks: Liquidation Baneful Bunker Recover Poison Jab	Attacks: Sludge Bomb Flamethrower Dragon Pulse Protect
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: Poisonium Z