Attacks Learned by Leveling Up
Raichu is only able to learn four attacks by leveling up: Thundershock, Tail Whip, Quick Attack and Thunderbolt. These attacks are "prepackaged" on all Raichu at Level 1 and can be re-taught via the Move Relearner in Pastoria City. Raichu found in the wild using a device such as an Action Replay will also know these four moves regardless of level.
Attacks Learned by Hidden Machine (HM)
Raichu is able to learn two of the game's eight HMs: Strength (HM04) and Rock Smash (HM06). Both of these attacks can be used outside of battle to clear obstacles from the player's path. In battle, both Strength and Rock Smash are physical attacks that deal 80 and 40 damage, respectively, with Rock Smash having a 50 percent chance of lowering the opponent's defense.
Attacks Learned by Technical Machine (TM)
A wide variety of TM options are available to Raichu, with several viable choices for competitive players. Notable attacks include Focus Punch (TM01), Iron Tail (TM23), Thunder Wave (TM73) and Grass Knot (TM86). Grass Knot is especially notable, as it enables Raichu to deal heavy super-effective damage to Pokemon it would otherwise be powerless against, such as the Ground-type Hippowdon and the Water-and-Ground-type Swampert.
Pre-Evolution Attacks
There are several useful attacks that Raichu can learn prior to evolving. As a Pichu, it is able to learn Charm, Nasty Plot, Sweet Kiss and Uproar. Of these, Nasty Plot is highly popular among players, as it effectively doubles Raichu's mediocre Special Attack stat, enabling it to deal more damage with attacks such as Thunderbolt and Grass Knot. As a Pikachu, a potential Raichu can learn Growl, Feint, Slam, Agility and Discharge.
Attacks Learned by Breeding
Pokemon are also able to inherit certain attacks from their parents that they would otherwise be unable to learn. These "egg moves" come prepackaged on a Pokemon upon hatching. Raichu has three particularly useful egg moves: Reversal, Encore and Wish. When combined with Endure or the item Focus Sash, Reversal becomes a powerful 200-damage Fighting-type attack. Encore traps an opponent into repeating the same move for two to five turns and Wish heals half of the defending Pokemon's Hit Points on the following turn.