The principal difficulty of having a Pokémon pick up your groceries for you isn’t getting it to understand the concept of a grocery list, but getting it to understand the concept of capitalism.
One might assume that Meowth is the exception, given that Meowth is literally the capitalism Pokémon; the trouble here is that, while Meowth does understand capitalism, Meowth also understands shoplifting.
This is because shoplifting is a vital feature of capitalism.