Alolan Raichu

Despite an additional Psychic typing over Kantonian Raichu, Alolan Raichu is not meaningfully different in any way, with the same Electric-type moves and no Psychic-type fast moves. It can't have any fancy hats, either.

Best PvE Offensive Moveset

• Thunder Shock is superior to Spark and Volt Switch in every way on offense
• Wild Charge is one of the best charge moves in the game and should be prioritized over Thunder Punch.
• Psychic is a good move, but it lacks synergy with Alolan Raichu's Fast Moves 
• Grass Knot can provide wider coverage, but you will probably just go with other options when you want a Grass attacker.  
• Trailblaze is inferior.

Best PvE Defensive Moveset

• Volt Switch is superior to Spark and Thunder Shock in every way on defense. 
• Wild Charge is on par with Thunder Punch, trading damage for lower energy cost.  
• Grass Knot offers some interesting coverage against weaknesses to Ground-types and Tyranitar. 
• Trailblaze is harder to dodge than Grass Knot, but it's also weaker.
• Psychic is a good option due to its high power and 2 bars

Volt Switch is great in PvP, and despite having slightly lower energy gains compared to Thunder Shock, it adds a lot of consistency to Raichu's performance with its higher damage output. Spark is strictly inferior to both other options.

Thunder Punch is needed to bait shields thanks to its lower energy cost, in addition to benefiting from STAB. Psychic and Grass Knot have great stats and add extra coverage, the former on Grass, the latter on Ground, both commonly used to counter Raichu. Wild Charge hits very hard if you're not concerned about getting walled by those.