The Pokémon Sword Expansion pass is for Pokémon Sword and not Shield. Vice versa is also true. If you buy one, you cannot play it on the other.
Today, Nintendo Support (via Hachima) warned people about confusing the two and making the incorrect purchase.
なお、ゲームのメニュー画面右下にある「エキスパンションパス」と書かれたバナーから購入すると、正しい方の『エキスパンションパス』を購入することができます(eショップの購入画面にジャンプします)。#ポケモン剣盾 #エキスパンションパス pic.twitter.com/kFUNXuBERj
— 任天堂サポート (@nintendo_cs) June 9, 2020
Nintendo Support added that if you simply purchase Expansion Pass in the game menu screen’s lower right banner, you will purchase the correct one in the eShop.
Unfortunately, as noted on the official support page, Nintendo is not giving refunds for mistaken purchases. The North American page clearly states, “We are unable to provide refunds or exchanges for mistaken purchases.”
Earlier this year, the official Japanese Pokémon site also warned players not to purchase the wrong expansion pass.

As Kotaku previously reported, Pokémon Sword and Shield’s expansion pass, The Isle of Armour, will see new pocket monsters and adventures when it’s released on June 17. Be sure you get the right one!
Why on earth would you do something like this?
Wouldnt it be crazy if they just let you buy the DLC once and it unlocked the right content based on what cartridge you had in.
Nah I wanna buy it twice!
Hopefully they release some kind of Pokemon Lance/Dagger/Blade version or something so I can buy it a third time
Or even sell a single version of the game that let you pick which variant you wanted to play.
You’ve been warned by Nintendo Jiggle Counter you can’t be buying the wrong one if you currently own Pokemon Sword or Pokemon Shield they won’t offer you refunds if you choose the wrong Expansion Pass.
I’ve already made the right choice and since I already own Pokemon Shield I’ve chosen the Pokemon Shield Expansion Pass and definitely can’t wait to catch more Pokemon making a return like Kangaskhan in the Isle of Armor Part 1 DLC which comes out for Nintendo Switch in 6 days.
I would love to stay and chat but I’m getting ready for the Pokemon Shield Expansion Pass Isle of Armor DLC Part 1 to come out for the Nintendo Switch in 6 days.
Let’s meet again another time djbear I look forward to it.
Capitalists going to capitalise, I suppose!