Pokémon : S5 | E56 – Pop Goes the Sneasel

The group continues towards Silver Town, and along the way, they notice a bunch of people gathered at a large closed gate. When they get there, Ash asks a pair of bystanders what's going on. The men explain that everyone is waiting at the Ho-Oh Shrine to see the official Johto League Silver Conference torch. Ash and his friends decide to wait with the growing crowd. A shrine attendant finally opens the gate and explains that the torch runner is currently delayed. While this is happening, Togepi runs through the gate, and Pikachu follows after it. The attendant notices the two rush inside and cuts them off in time. The group enters the area to collect Togepi and Pikachu before apologizing to the attendant.

Two Trainers suddenly rush down from the shrine. They tell the guard they cannot train at the shrine and rush off to the Pokémon Center to treat their injured Pokémon. The attendant is deflated, admitting that all the Trainers so far have been running away in fear. As he goes to ask Ash for a favor, another Trainer with his Houndoom steps forward and offers his assistance. He introduces himself as Harrison from Littleroot Town in the Hoenn region. Brock believes he has heard of Hoenn and suggests it's somewhere on the other side of the ocean. With Harrison now on board, he and the group follow the attendant to the shrine building. The attendant explains that the torch runners are all ready to go, but they cannot reach the flame. He details that the Ho-Oh Shrine was where a terrible war was fought. People ravaged the place so badly that the Pokémon suffered because of it and the vegetation was wiped out. Ho-Oh appeared after a battle and unleashed a rose-colored flame that set the area alight and destroyed the weapons of war. From the ashes came new life and the area was restored to nature. But a bit of a tree was left burning for the longest of times. And they placed the fire in a shrine declaring it the Sacred Flame that is now housed in the Ho-Oh Shrine.
(Source: Bulbapedia)