PK26

Pokémon: Pikachu, What's This Key? (Japanese: ピカチュウ、これなんのカギ？ Pikachu, What's This Key For?) is the 26th Pikachu short of the Pokémon anime. It debuted alongside Pokémon the Movie: Diancie and the Cocoon of Destruction. It became available to watch through Pokémon TV on February 2, 2015.

Blurb
In Pokémon: Pikachu, What's This Key?, Pikachu and friends meet Klefki, a Pokémon who holds the keys to the mystical worlds of Mythical Pokémon!

Plot
and his friends are playing on a small playground outside a rustic cottage while their Trainers are resting there. While playing, Pikachu and accidentally knock  off a roundabout. Chespin, seeing this as a chance to be mischievous, gets some distance between the roundabout and himself. At this point, has joined Pikachu and Fennekin on the roundabout. Chespin runs and jumps onto the roundabout, causing it to spin out of control. Dedenne cannot hold on and gets thrown off into a bush beside the rustic cottage. Seeing this, Pikachu lets go of the roundabout to check on Dedenne.

As Dedenne recovers, it runs around the side of the cottage and finds an open cellar window. Being curious, it jumps down into the cellar which seems to be used for storage. Inside, there are numerous artifacts such as golden necklaces, swords, and a grand assortment of pottery and furniture. Dedenne hops over to the left hand corner and gets a key stuck on the end of its tail. Pikachu follows, having brief difficulty entering through the barely opened cellar window, and falls into the cellar getting his head caught in a ceramic vase. Dedenne makes a laughing noise which alerts a snooping that it is the Pokémon inside the cellar. Meowth is accompanied by Jessie's Wobbuffet and James' Inkay behind a bush outside of the cellar. They watch as Pikachu and Dedenne leave the cellar, the golden key still clung to Dedenne's tail.

Pikachu and Dedenne join up with the other Pokémon, and all of them become fascinated with the sparkling, golden key on Dedenne's tail. As they stare, a wild comes down and snatches the key, unable to separate it from Dedenne. Pikachu grabs onto Dedenne and both are pulled, along with the key, into the air by Klefki. In Klefki's efforts to shake the key loose from Dedenne, Pikachu uses and knocks Klefki to the ground, freeing the key and Dedenne. Pikachu catches the golden key and Klefki approaches Pikachu, trying to retrieve the key from him. Pikachu backs away as Klefki follows him in a circle and finally Pikachu offers the key to Klefki. With great excitement, Klefki happily accepts and pushes Pikachu to an opening in the woods, prompting the other Pokémon to follow.

In the middle of the path, a floating keyhole awaits the group. Klefki holds up both keys in its possession and figures out which one fits. The golden key that Dedenne found in the cellar, and Pikachu gave to it, was an exact fit. Klefki inserts the key and turns it, opening a bright purple vortex that pulls the group of Pokémon in. From behind a decorative planter, Meowth, Wobbuffet, and Inkay watch in awe. Before the vortex disappears, they jump into the spiraling portal as well before it closes and leaves the keyhole behind.

The world they arrive in is dreamlike, with a pink sky and vegetation of all shapes and colors. Many of the objects in this realm are fittingly key-shaped and the narrator states that it is Klefki's world. Klefki shows the group a mountain of keys that it has collected, surpassing many trees in height. Chespin picks up a stray key that is lying next to the pile and throws it towards the top, trying to put it back. In doing so, he causes the mass of keys to fall down and nearly engulfing him. Another stray key flies from the pile and hits Pikachu in the head. Dedenne accidentally catches it and jumps up and down with happiness. It then proceeds to try using the key in a nearby keyhole. Proving unsuccessful, Pikachu has to let Dedenne know that it is the wrong keyhole. In searching for the correct keyhole, many other keyholes are seen across the expanse of Klefki's world. Pikachu finds the correct keyhole and directs Dedenne to use the key.

A yellow hole in the ground appears underneath Pikachu and Dedenne and they fall into another realm. This time, there are many pillars of stacked boulders poking through the clouds. Pikachu and Dedenne happen to be standing on the top of one of these pillars. Pikachu gets to close to the edge before realizing that there was a drop-off and falls onto the clouds which bounce him back into the air. Entertained by the magical clouds, Pikachu continues to bounce and once again accidentally falls, this time into a chasm between the clouds. With nothing below to catch him, the Mythical Pokémon appears and returns Pikachu to safety. Pikachu and Dedenne return to Klefki's world to regroup with the others.

Klefki holds up the other key that it had before obtaining the key Dedenne found in the cellar, desiring to enter the world that to which the key belongs. Preparing to go, the others are still unaware of Meowth, Wobbuffet, and Inkay's presence in Klefki's world. Meowth sees this as an opportunity to find treasure in one of the many worlds the keys can open. Pikachu and friends enter into a world full of ice and snow with plenty of sliding fun for the group. They soon meet another group of Pokémon (,, , and ) that live in this world. Pikachu falls off of one of the icy slopes and onto the back of the wild Tyrunt, followed by and, who have fallen on top of Pikachu. Out of disorientation, Pikachu lets out a burst of electricity and shocks all of them. This frustrates Tyrunt, who sees Pikachu as a threat at first. Chespin comes in behind the rest and falls into Tyrunt's open mouth, stabbing Tyrunt's tongue with his pointy head spikes.

Meanwhile, Meowth has found a key that is "gleaming gold", expecting the key to lead them to extravagant riches. Instead, this key leads them to a mysterious water world with floating spheres of water. They see the Mythical Pokémon flying between one sphere to the next, before they are launched by a  into the sky.

Back in the ice world, Tyrunt is retaliating and getting even more angry before the Pokémon destroy the large structure of ice they were standing on. All of them fall except for Tyrunt and Pikachu, who are left on a chunk of ice only big enough for the two of them. Pikachu prompts Tyrunt to jump by going in Tyrunt's mouth and electrocuting it. They fall safely to the ground with Tyrunt slightly dazed when the Mythical Pokémon Jirachi appears to play with the others.

Still in search of treasure, Meowth finds another key and opens up a world that is red and black, with no ground and large, strangely shaped structures floating around in the air. The Mythical Pokémon scares them back to Klefki's world, obviously not happy that they have intruded. When they return they notice that the keyhole they just left is starting to fade. This means trouble for all of them, since the keyholes are about to disappear.

In the ice world, Klefki notices that time is running out and alerts the others. In a hurry to leave, the entire group goes to the keyhole and due to its weight, Tyrunt accidentally breaks the ice underneath them. Falling to the ground, they are unable able to reach the keyhole which Klefki has opened. Using teamwork, Tyrunt lifts all of Pikachu and his friends into the keyhole in time for them to return to Klefki's world. Although Pikachu and the others didn't know that Meowth was in Klefki's world, he greets them and asks them where they went. Pikachu asks him how he got into Klefki's world. Meowth doesn't answer, instead he points out that all of the keyholes are beginning to disappear. In an effort to open the keyhole, Meowth snatches the key from Klefki and runs to the original keyhole. Meowth trips on his way there and almost loses the key in the large pile of keys that Klefki collected. Luckily, Pikachu catches the key and they are able to return to their home world just in time for dinner.

Humans

 * (face never shown)
 * (face never shown)
 * (face never shown)
 * (face never shown)

Trivia

 * This is the first Pikachu short since Gotta Dance!! to feature humans.
 * This is also the first Pikachu short since Snorlax Snowman to feature and, though as in several other shorts featuring them, their faces are never shown.

Dub edits

 * The drawings that fans have submitted shown in the ending credits have been edited out.
 * The version of the episode used in Camp Pokémon cuts approximately a minute of footage: when Klefki tries to shake of Dedenne and Pikachu uses Thunderbolt, when Klefki falls to the ground electrocuted, when Pikachu and the others land on Tyrunt and electrocutes it, when Tyrunt snorts at Klefki, when Tyrunt blows away Pikachu and the others and the ice starts to collapse, when Pikachu uses Thunderbolt on Tyrunt and the falling ice lands on its head, and when Tyrunt tries to charge into them. This is likely due to the fighting in the cut footage being considered inappropriate for the app's intended audience.