There is a fire in the forest and the Pokemon are trapped. One Pokemon comes, using its power to create vines to stop the fire, in which it succeeds. The vines disappear and the Pokemon is exhausted. However, a tree falls, so the Pokemon vanishes into thin air. Later, the Pokemon appears and forms the vines again to keep the rain at bay while it rests. The gang is walking on a road and Brock tells there is a bike rent nearby, so they should check it out. However, they see Officer Jenny and the closed road - it rained so much the mud cannot be passed. However, she redirects them at a de-tour, where they can pass safetly.
As they walk, Pikachu senses something and runs, so everybody follows him. Suddenly, they are stopped by a woman and Plusle - Max tells she is a Pokemon Ranger. Ash tells Pikachu ran off, so the Ranger calls someone to tell the problem. The gang introduces themselves and the Ranger is Solana - she allows them to continue. Pikachu passes through the vines, though Team Rocket is stuck between them. They planned an ambush, but their plan is now foiled. Max tells that the Rangers help people and Pokemon in natural disasters, to which Solana confirms. They all reached the vines, but they are too thick to pass. Still, Solana tells Celebi, the Guardian of the Forest, lies inside and have to go save it.
Solana analyses the Pokemon via a device which helps the Ranger to receive data if it can help them. She sends a disc and waves with the device, attempting to capture Linoone. She spins the device and with some time passing, she captures them. Plusle uses Helping Hand, so the Linoone slash the vines - the path is clear, so they continue. Pikachu is seen to found the Pokemon, Celebi. He goes to it and sees it awake, but weak, so goes to find help. Solana tells them Celebi made the vines grow, so she was sent to investigate. They realize Pikachu went only to help Celebi, as he sensed something wrong. Solana asks to keep Celebi a secret, being a Mythical Pokemon. They agree to, and suddenly encounter Team Rocket stuck between vines. They tell they were planning an ambush, but are stuck. Solana decides to free them - Linoone slash the vines. She demands them to go away, so they run away.
Pikachu returned to Celebi with berries. Celebi eats one and feels better already. Solana sets Linoone free, as they are not required anymore. Solana decides to capture other Pokemon, like Dugtrio and Diglett. She spins the device and they are captured. Plusle uses Helping Hand, so the Dugtrio and Diglett dig. They all go inside the hole. Pikachu makes grimasses to entertain Celebi. Celebi and Pikachu lauch, but see that the Dugtrio and Diglett dug a tunnel - everyone comes to them. Ash re-unites with Pikachu and everyone spots Celebi, telling they came to help it. That night, Solana analyses Celebi and tells it will feel better after some sleep. Solana suspects it might came from the past to present after some trouble befell it.
Next morning, everyone wakes up and Celebi is happy, cheerful and healthy - the vines soon vanish. Suddenly, it is captured by Team Rocket. They go away, but Solana runs and uses some vines to go to the machine. Plusle uses Thunderwave, stopping the machine. Team Rocket are blasted off by the explosion, but fall back. Jessie sends Seviper and James his Cacnea, while Brock his Marshtomp. Seviper uses Poison Tail and Cacnea Pin Missile, but they both miss. Pikachu uses Thunderbolt and Marshtomp Mud Shot, hitting both Pokemon. Pikachu uses Iron Tail, attacking Cacnea. Pikachu uses Volt Tackle, blasting them off. The machine bursts into flames, so Celebi uses the same move - it creates vines to stop the flames. Also, it uses Healing Bell, to renew the woods. They all thank Celebi and it vanishes.
Celebi traveled back to the time it lived. Solana tells on the phone she achieved her task. Max is sad, he wanted to play with it more, with May feeling the same. Ash tells they will see Celebi again. At the end of the day, the gang is seen riding the bikes as a shortcut.