Another reference you might check out is this list of which sets have been released in which languages
(Source: I've been collecting Pikachu for ~8 years now and own almost all of them at this point..) I do agree he has way too many cards
For example, in a game of Mystery Booster 2 Limited, Toralfs Disciple can conjure Lightning Bolts into your deck, even though the card Lightning Bolt isnt found in Mystery Booster 2 and isnt normally legal in the Limited format
Additionally, it's useful to have another low Energy attacking Pokmon, like Mew ex from the Mythical Island booster pack, to deal damage while searching for all the Mewtwo, Ralts, Kirlia and Gardevoir cards needed to activate the synergistic Psychic abilities
When the last is removed, cast it without paying its mana cost.) Target player draws three cards
The cards above may be generally good, but theres always another card thats just perfect for your specific deck