In Alola, Raichu has a dual-type Electric/Psychicregional form. It evolves from Pikachu when exposed to a Thunder Stone. All Pikachu in Alola will evolve into this form regardless of their origin. It is the final form of Pichu in the Alola region.
Raichu is a bipedal, rodent-like Pokémon. Raichu is covered in dark orange fur with a white belly. Its bifurcated ears are brown on the outside, yellow on the insides, and end in a distinctive curl. There is a circular yellow marking on each cheek where its electric sacs are, and it has a triangular, dark brown nose. Its arms and feet have patches of brown fur at the end, and the soles of its long feet are tan with a circular orange pad in the center. On its back are two horizontal brown stripes. Its long, thin tail has a lightning bolt-shaped end. This lightning bolt is chipped on females. Raichu exudes a weak electrical charge from all its body and glows slightly in the dark.
Raichu's tail is used to gather electricity from the atmosphere, or it can be planted in the ground to search for electricity. It also protects Raichu from its own high voltage power. Raichu can store over 100,000 volts of electricity, enough to knock out a Copperajah. If Raichu's sacs are fully charged, its ears will stand straight up and its muscles become stimulated. However, it will become aggressive if it has stored too much electricity and stress. To keep from reaching this state, it discharges electricity through its tail into the ground. This leads to scorched patches near its nest. Being the result of evolution via Evolution stone, Raichu is rarely found in the wild, though they can be found in forests and woodlands. The main reason Raichu is rarely seen in the wild is because people prefer the look it had as Pikachu.
In Alola, Raichu has lighter coloring and more rounded features. Its eyes are blue with yellow half-circles along the bottom. It has large yellow ears with an inner spiral toward the base and brown on the inside. These ears are thicker and less pointed than a standard Raichu's ear. In addition to its white belly, Alolan Raichu has white markings on its paws with bright yellow lines between its digits. The stripes on its back have also turned white, and there is a small, white circular marking on each heel. The lightning bolt-shaped tip of its tail has rounded edges. By collecting its psychic power in its tail, it is able to ride it like a surfboard and float in the air. While its cheek sacs are still used to store electricity, rubbing them releases a sweet aroma while also getting a light shock. This is also thought to be connected to its Psychic abilities.
Alolan Raichu's origins were initially a mystery at the time. The people of Alola suggested it ate too many sweet and fluffy pancakes, especially those made with a secret Alolan recipe. However, researchers believe the change is related to Alolan Raichu's diet in general. It is also believed the weather and climate of the Alola region played a role in the transformation. Alolan Raichu is capable of unleashing star-shaped thunderbolts. It is also known by the name hodad.
A Raichu appeared in Pika and Goliath!, under the ownership of Sho, who sought to have possession of one Pokémon each from the Pikachu evolutionary line. It battled Ash's Pikachu twice in that episode, with Raichu being victorious the first time and Pikachu triumphing during the rematch.
In Destination: Coronation!, Visquez used a Raichu to defeat a Trainer's Hypno. It then went up against Ash's Pikachu, but Ash withdrew Pikachu and sent out Gengar in his place; the Shadow Pokémon then managed to defeat Raichu.
In Gotta Catch a What?!, multiple Pikachu evolved into Raichu using the Thunder Stones they had dug up.
In The Legend of Thunder!, a Raichu was one of the Electric Pokémon that were lured by the "Miracle Crystal" that Attila and Hun were using. Raichu tried to hit the robot controlled by Attila to save the other Pokémon from being kidnapped, but his attack ricocheted off.
Lt. Surge has a Raichu, which was first seen in Silph Co. in Go for the Golbat. However, it never participated in battles until fighting the Masked Man in his Mahogany Hideout, where it helped Surge break in and seemingly backed the mastermind into a corner, until his Houndour called upon dozens of wild Houndour to thwart Surge, instead. The former Team Rocket triad member barely escaped with his life after having many of his Electrode self-destruct.
Raichu originally had an evolved form named "Gorochu" (Japanese: ゴロチュウGorochū), which would have had two horns and fangs.Ken Sugimori stated that while there was nothing wrong with its appearance, it was nonetheless omitted from Pokémon Red and Green Versions, as the staff found that the game balance was better without it, and the limited game space meant that some Pokémon originally designed to evolve twice were changed to evolve only once.
Raichu's FireRed and Sun Pokédex entries discuss Raichu's electricity being able to knock out an Indian elephant. In Pokémon Legends: Arceus, this is changed to Copperajah, which is based on the Indian elephant.
Several Pokédex entries claim Raichu can discharge up to 100,000 volts. However, its Stadium entry claims it can only discharge up to 10,000 volts. This is likely a translation error due to the way numbers are read in Japanese, where 100,000 literally reads "ten ten-thousands".
Although Pikachu is the starter of Pokémon Yellow, it is not possible to directly evolve it into Raichu in the game, and must be traded in from Red and Blue. This inability to evolve Pikachu is a reference to Ash's Pikachu in the anime.
According to Ken Sugimori, he asked Atsuko Nishida to design Alolan Raichu since she was the one who had worked on the original Raichu design. Nishida insisted that Raichu "has always been cuter than people might think", and designed Alolan Raichu to emphasize Raichu's cuteness; in particular, she designed it with the motif of bread. The in-game lore of people believing that its evolution is induced by eating pancakes was added afterward to play up the concept. The fact that Alolan Raichu was designed after bread may have also inspired the sweet fragrance it can release from its cheeks, as well as the look of its paws which resemble whipped cream decorations, cream puffs, or baozi.
Raichu may be a combination of 雷 rai (thunder) and チューチュー chūchū (onomatopoeia for the squeak of a mouse).