Trials and Determinations! (Japanese: ライチの大試練！一番ハードなポケモン勝負！！Lychee's Grand Trial! The Hardest Pokémon Match!!) is the 36th episode of the Sun & Moon series, and the 975th episode of the Pokémon anime. It first aired in Japan on August 3, 2017 and in the United States on October 21, 2017.
The day of Ash’s grand trial against Kahuna Olivia is finally here, and it’s a Double Battle! Olivia’s Probopass and Lycanroc face off against Ash’s Rowlet and a strangely aggressive Rockruff. After Olivia sets a trap on the battlefield, Ash instructs Rowlet to grab Rockruff by the scruff of the neck so they can fly above it. They defeat Probopass, but Rockruff lashes out at Rowlet and knocks it out!
Rockruff feels terrible about this but soon regains its focus and takes Lycanroc down. Ash wins the grand trial and the Rock-type Z-Crystal, and Olivia has an explanation for Rockruff’s unusually aggressive behavior—she thinks it’s going to evolve soon!
Ash is training with Rowlet, trying to perfect Bloom Doom. After the Z-Move fails, Mallow gets frustrated at Ash and informs him how to pose properly. When Ash's Pokémon join him after the Z-Move practice, Rockruff bites Ash and he notes that Rockruff is more energetic than usual. Before the grand trial, Olivia is seen at the Ruins of Life, praying to Tapu Lele, the island guardian. Ash and his classmates then head over to the Ruins of Life where the grand trial will take place. They head into a forested area where the rectangular stone battlefield is surrounded by large amounts of flowers and ancient stone pillars. When Olivia comes onto the battlefield with Lycanroc, Rockruff becomes worked up and starts barking. Rockruff bites Ash again when he tries to control it and then leaps out of Ash's hands.
Ash facing Olivia
For the battle, Olivia first sends out Probopass, but before Ash can send out Rowlet, an eager Rockruff runs onto the field. Then, to everyone's surprise, Olivia reveals that the battle will be a Double Battle due to Ash's previous successes and impressive handling of Z-Crystals. Olivia then sends out Lycanroc while Ash sends out Rowlet. Ash has Rowlet use Leafage, with Rockruff using Rock Throw. Lycanroc uses Rock Slide to destroy the incoming attacks and blows away both Rowlet and Rockruff. Probopass uses Stealth Rock and creates large rock pillars which surround Rowlet and Rockruff. Rockruff tries to run out but gets hit by the pillar. Ash orders Rowlet to grab Rockruff and fly out of the trap whilst using Leafage. Leafage makes contact on Probopass. Probopass reacts by making using Magnet Bomb with its Mini-Noses but Rockruff uses Rock Throw to blow them away. However, one remains and uses Magnet Bomb causing damage and pushing Rockruff and Rowlet back into the pillar trap.
Rowlet and Rockruff have taken a large amount of damage and look exhuasted but Ash is still fired up and ready. Probopass uses Zap Cannon while Lycanroc uses Accelerock. Rowlet quickly reacts with Leafage which makes contact. Lycanroc uses Probopass' Mini-Noses to jump into the sky to catch Rowlet and attack with Accelerock. Probopass then launches its Zap Cannon to Rowlet but Rockruff quickly pushes one of the Mini-Noses to the Zap Cannon to protect Rowlet. Rowlet thanks Rockruff but Rockruff barks loudly back. Rockruff's impatience and fieriness has elevated dramatically.
Olivia tells the Mini-Noses to surround Rowlet and Rockruff. Olivia then uses her Z-Move with Lycanroc. Ash tells Rowlet to fly in the air with Rockruff. Lycanroc uses Continental Crush and Rowlet and Rockruff stay directly underneath the rock but quickly fly away before it lands, thus not taking any damage while crushing the stone pillars in the process. Olivia reacts by making Probopass use Giga Impact and Lycanroc use Rock Slide. Ash counters by ordering Rowlet to use Leafage and Rockruff to use Bite on Lycanroc. Leafage destroys the Rock Slide but Rockruff gets hit by Giga Impact. Rockruff is thrown against the cliff-face but comes back and uses Bite on Lycanroc. Probopass uses Magnet Bomb on Rowlet but Rowlet manages to maneuver the Mini-Noses to attack Probopass instead. Ash then decides to use the Grass-type Z-Move with Rowlet. To stop Ash from using it, Probopass uses Giga Impact but doesn't reach Rowlet in time, making it unable to battle.
When Rowlet tries to lift Rockruff into the air, Rockruff resists and uses Bite on Rowlet. This makes Rowlet unable to battle. Rockruff realizes his mistake and becomes upset. However, Ash cheers up by posing like Rockruff when it first learnt Rock Throw and states that he will battle alongside Rockruff. Determined again, Rockruff uses Rock Throw while Lycanroc counters with Accelerock. They both make contact. Rockruff uses Bite but misses and Lycanroc quickly reacts with Rock Slide. But Rockruff uses the rocks to jump towards Lycanroc and delivers a Rock Throw at close range. As a result, Lycanroc falls onto the battlefield and is declared unable to battle. Ash wins his Grand Trial. However, Rockruff soon faints in exhaustion.
Olivia and Ash's friends congratulate him for the win, and Olivia gives Ash his fourth Z-Crystal, Rockium Z. Ash shows Rockruff the Z-Crystal, but this doesn't help it feeling upset for attacking Rowlet. Olivia tells Ash that Rockruff is going to evolve soon. Professor Kukui adds that Rockruff become more aggressive and independent when they are close to evolving. After the battle, Tapu Lele's sparkle rain down on the battlefield. Ash and friends spot Tapu Lele in the sky for a brief moment.