A Masked Warning! (Japanese: グラジオとシルヴァディ！戒めの仮面！！Glazio and Silvady! The Mask of Punishment!!) is the 47th episode of the Sun & Moon series, and the 986th episode of the Pokémon anime. It first aired in Japan on October 26, 2017, in New Zealand on March 1, 2018, and in the United States on March 27, 2018.
When Ash gives Lycanroc a bath, an accidental splash of dirty water unleashes Lycanroc’s surprisingly red-hot temper!
Then, when our hero wonders aloud what Gladion is up to, Nebby teleports Ash and Pikachu to him. They meet Silvally, a Pokémon created to defeat Ultra Beasts—and Gladion is convinced that Nebby is one! Suspicious, Gladion wants to know what Ash is up to, and our hero suggests a battle so he can find out!
Ash’s Dusk Form Lycanroc faces off against Gladion’s Silvally. Lycanroc battles magnificently, but another temper tantrum betrays its inexperience, and Silvally wins. But Gladion decides Ash is trustworthy, and their friendship starts to grow…
Lillie writes in her diary about the events of the previous episode, regarding the group's visit to Aether Paradise. The next day, outside Professor Kukui's house, Ash is giving his Pokémon a bath. After finishing Pikachu, Litten isn't keen to have a bath, but Lycanroc is. Litten becomes startled and knocks over the water container which causes Lycanroc to become dirty. This leaves Lycanroc angry, with its eyes turning red, and it starts attacking Litten. Ash tries to calm Lycanroc down as it tries to chase Litten. Ash eventually calms Lycanroc down before cleaning its mane. Ash begins to think about Gladion, which causes Nebby to teleport Ash to his location at Ten Carat Hill. Ash lands on top of a group of Pinsir, which makes them angry, but Gladion saves him by using Type: Null.
Ash thanks Gladion for saving them and sees his Type: Null, who stares at Nebby, scaring it. Nebby eventually calms down as Gladion tells Ash that Nebby could be an Ultra Beast, agitating Gladion. Gladion is surprised to learn that Ash made a promise to Solgaleo and Lunala, and Ash proceeds to explain how he met Nebby. Ash introduces him to Lycanroc and fills Gladion in on how Lillie is doing. Gladion informs Ash that Lillie was previously attacked by an Ultra Beast, which caused her to become scared of Pokémon. Gladion regrets not doing anything to help, but it was Type: Null or "Silvally" that saved her. Gladion vows that it won't happen again and tells Ash that he will defeat every Ultra Beast, even Nebby if it comes down to it. Ash, unamused, immediately jumps to Nebby's defense.
Gladion won't go into detail about Silvally, but explains it was created to defeat Ultra Beasts. Ash apologizes for suddenly appearing as Gladion starts to demand answers about Ash and why unusual things are happening to him. Ash, unable to provide any answers to the given questions, suggests they have another battle, which Gladion agrees to. Gladion uses Type: Null whilst Ash battles with Lycanroc. The battle begins with Type: Null blocking Rock Throw with its own attack before using Swords Dance. Lycanroc dodges Type: Null's Crush Claw before attempting to attack with Bite, which gets countered. After dodging another attack, Lycanroc lands a direct attack on Type: Null, but is thrown in the water nearby. This causes Lycanroc to get dirty, which makes it angry once again.
Lycanroc starts to ignore Ash's instructions and begins to attack Type: Null. Type: Null manages to defend itself as Ash tries to calm Lycanroc down. The commotion causes Nebby to start crying, with the sound waves actually removing the dirt from Lycanroc's fur, calming it down. With the issue solved, Ash requests that they continue the battle, and they do so. After using Swords Dance again, Type: Null is able to defeat Lycanroc with Crush Claw. Recalling Type: Null, Gladion thanks Ash for the battle, noting that their Pokémon both have their own advantages before departing. Gladion asks Ash not to mention seeing him or Type: Null, and Ash promises to honor his request. Ash prepares to go home, before realizing he doesn't know how to do so. Nebby has fallen asleep again, and Ash starts begging for it to wake up and take him back home. Ash is eventually able to get back home with the help of Lycanroc.