From Bulbapedia, the community-driven Pokémon encyclopedia.
The island challenge amulet
The island challenge (Japanese: 島めぐり island-visiting) is a rite of passage for burgeoning Pokémon Trainers in the Alola region. Trainers can partake in these rites when they turn 11, which involve traveling through each of the four major islands of Alola and completing various trials (Japanese: 試練 trial) on each. The goal of those taking the island challenge is to become the strongest Trainer, known as the island challenge champion.
Participants in the island challenge are given an island challenge amulet to identify them. The island challenge consists of a number of trials on each of the Alola region's four islands, with each usually headed by a Trial Captain. Trials are not limited to Pokémon battles; they may involve finding designated items or a test of knowledge, among other tasks. Trials are all difficult tasks that require Trainers to prove themselves. To complete the trial, the Trainer must defeat a Totem Pokémon in an SOS Battle.
The final trial on each island is called the grand trial (Japanese: 大試練 grand trial). In the grand trial, the Trainer must battle the Island Kahuna. If they complete an island's grand trial, they are recognized as having cleared all of that island's trials and can move on to the next island.
During a trial, the player cannot flee from battles (including with Teleport), Roar will fail, Wimp Out and Emergency Exit will not activate to allow a Pokémon to flee nor switch, and wild Pokémon cannot be caught. If the player leaves the trial site before completing the trial, they have to start the trial again. Upon completing a trial, the player earns a Z-Crystal.
Similar to Badges, completing trials can expand the amount of items purchasable in Poké Marts, and completing grand trials will make outsider Pokémon obey the player.
In this trial, the player must find and battle two YungoosS/Alolan RattataM and a GumshoosS/Alolan RaticateM. Along the way, the player will face two Team Skull Grunts and battle one of them. Once defeated, the two grunts will help the player finish the trial.
In this grand trial, the player has to defeat Island Kahuna Hala.
This trial begins after Lana leads the player onto the trial site. Having already traversed most of Brooklet Hill and dealt with two Wishiwashi on the way to the trial site, the trial consists of simply defeating the Totem Pokémon.
In this trial, three pairs of dances are performed, and the player has to identify which actor is different between each pair.
In this trial, the player has to find four ingredients hidden in the trial site. After collecting all four, the player has to combine the ingredients to create aroma that lures the Totem Pokemon.
In this grand trial, the player has to defeat Island Kahuna Olivia.
In this trial, the player has to help Sophocles open a security door by answering several audio questions and fighting Pokémon in between. After answering the last question, the player battles the Totem Pokémon. After defeating the Totem Pokémon, Molayne will also congratulate the player and gift them with a Steelium Z.
In this trial, the player has to take a photo of the Totem Pokémon in the Abandoned Thrifty Megamart. After drawing the attention of the Totem Pokémon by photographing other Ghost-type Pokémon in the area, the player follows the Totem Pokémon to the back room and battles it after taking a photo of it.
In this grand trial, the player has to defeat Island Kahuna Nanu.
In Pokémon Sun and Moon, the player's experience with Poni Island's portion of the island challenge is a bit different than that of the other islands. While Poni Island does have a Trial Captain named Mina, who the player briefly meets, she does not have any trial for the player. Instead, Hapu's grand trial is the player's first challenge on Poni Island. After that, the player is confronted by a natural trial at the Vast Poni Canyon on their way to the Altar of the SunneS/Altar of the MooneM.
In Pokémon Ultra Sun and Ultra Moon, however, Mina will have a full trial for the player.
In this grand trial, the player has to defeat Island Kahuna Hapu.
Vast Poni Canyon trial
At the end of the Vast Poni Canyon, before the player can reach the Altar of the Sunne/Moone, the player must defeat a Totem Pokémon who guards the entry point. A Jangmo-o and a Hakamo-o will also assail the player before they reach the Totem Pokémon.
In the past, after clearing all trials and grand trials, usually challengers would head to the summit of Mount Lanakila and have a final trial, where they have to defeat all four kahunas in a row in order to be acknowledged as an island challenge champion. However, this final trial ceremony has now been replaced with the newly founded Pokémon League. Becoming the Champion earns the player the Island Challenge Completion stamp, getting all outsider Pokémon regardless of level to obey the player.
In this trial, the player must find and photograph four elusive Pokémon. Upon capturing each Pokémon in a photo, they will attack the player. The first two Pokémon the player can find are Jangmo-o, who are followed by a Hakamo-o, with Totem Hakamo-o being the final subject.
In the anime
Ash facing Hala in the Melemele grand trial
In the anime, the island challenge is a way for Trainers to obtain Z-Crystals, and are said to have been created in order to raise Trainers to love and protect the islands of Alola as well as the people and Pokémon who inhabit them. The challenges are made up of lesser trials which must be passed before challenging the island kahuna in a grand trial. These trials are not presided by Trial Captains, and trialgoers are able to freely challenge a Totem Pokémon without having someone providing guidance or supervising them. Most Totem Pokémon are said to follow the lead of the Island Guardian.
All trials seen so far work similarly to the Vast Poni Canyon trial from the games, with Trainers being rewarded by the Totem Pokémon itself if successful in battle. However, Hala contradicts this by noting that it is rare for a Totem Pokémon to directly give the Z-Crystal to the Trainer themselves. Another difference lies in the fact that completing all trials in an island is not required for a battle with the island kahuna; Trainers will earn the right to face off against a kahuna after completing just one trial.
Ash is currently taking the island challenge in conjunction with his studies at the Pokémon School in the Alola region. He competed in his first trial in To Top a Totem!, in which he cleared the Verdant Cavern trial, earning a Normalium Z from the Totem Gumshoos. In Trial and Tribulation!, he battled against Hala in the Melemele Island grand trial and won. Hala was about to reward him with a Fightinium Z, but Tapu Koko switched it with an Electrium Z. His third trial took place in Currying Favor and Flavor!, when he cleared the Lush Jungle trial, earning a Grassium Z from the Totem Lurantis. He then faced Olivia in the Akala Island grand trial in Trials and Determinations!, earning a Rockium Z for defeating her.
Ash's classmates have completed some trials as well. For instance, Kiawe completed Olivia's grand trial on Akala Island prior to Alola to New Adventure!, receiving a Z-Ring and Firium Z as a reward. Lana completed the trial on Brooklet Hill in Big Sky, Small Fry! by defeating a Totem Wishiwashi in its School Form with her Popplio, receiving a Waterium Z from the Pokémon and a Z-Ring, made from her Sparkling Stone, from Olivia afterward.
In the manga
In the Pokémon Adventures manga
The island challenge debuted in the Sun & Moon chapter. Hala, Olivia, and Nanu orchestrated a tournament to be held at an Iki Town festival. The winner of the tournament will be awarded an island challenge amulet and be given the task of doing the island challenge in order to calm the guardian deities, who had been angered by something.
In other languages