Note:, I will put the moves in a group of what he/she/it has learnt in each region
KANTO
Thundershock
Thunderbolt
Agility
Quick attack
Thunder
Double-edge
JOHTO
Tackle
Leer
HOENN
Iron tail
Volt tackle
SINNOH
None
UNOVA
Electro ball
KALOS
None
ALOLA
Electroweb
Note: leer and tackle pikachu can not learn legitimately in the main series games I'm also fairly sure he/she/,it forgot them later on in the show.
Z-MOVES
Gigavolt havoc
10,000,000 volt thunderbolt
Breakneck blitz
Source: https://m.bulbapedia.bulbagarden.net/wiki/Ash's_Pikachu