Pokémon : S5 | E18 – For Ho-Oh the Bells Toll!

Ash and his friends rest at the Ecruteak Pokémon Center and they discuss the route to Mahogany Town. All of a sudden, they hear a weird noise that's coming from the outside. They see Nurse Joy and Chansey run by. Nurse Joy says that there is something up with the Tin Tower. Morty notices this too, and is greeted by his friend Eusine. Both venture inside the tower to investigate, and they notice a set of gold bells are vibrating. They go up onto the ninth floor, which houses the special Crystal Bells, and notice that the bells are missing. Morty orders his Gengar to find the culprits. Meanwhile, Team Rocket celebrates their little steal in the surrounding forest, thinking that they will get some Legendary Pokémon now. James explains that when the bells ring, it is supposed to summon Ho-Oh. So, they start shaking the bells, but no sound is coming out. Jessie grabs them and swings them around, but one slips out and breaks on a rock. All of a sudden, an eerie wind begins to blow, and the Tin Tower's bells fall silent.

The group arrives at the Tin Tower, but Eusine blocks their path. Morty appears and is glad to see Ash again, remarking his arrival is almost prophetic. He informs Eusine that Ash saw a Ho-Oh when he first began his journey. Eusine instantly frowns at Ash. Morty takes everyone back to his place where he shows them all a scroll depicting the ancient Crystal Bells. He explains that the bells contained within the Tin Tower were recovered from the Burned Tower after it was destroyed 300 years ago. Eusine declares that the ringing of the bells today indicates that Ho-Oh still watches over everyone. He adds that Ho-Oh's anger will only melt away when the hearts of humans and Pokémon alike become one. Eusine explains that Ho-Oh sent three incarnations of the north wind, volcanoes, and thunder, to maintain the peace, Suicune, Entei, and Raikou respectively. Ash declares that he met Suicune, and he points it out in a book with confidence. Eusine is infuriated, having spent a lot of his time tracking Legendary Pokémon, and declares Ash a liar. He challenges Ash to a battle to prove his worth. Meanwhile, in the forest, Team Rocket is surrounded by angry Bug-type Pokémon. Meowth translates and reveals the wild Pokémon are angry at them for breaking one of the Crystal Bells. The Pokémon all fire a String Shot at Team Rocket.
(Source: Bulbapedia)