When you trade a Pokémon from a Gen 1 game (Red / Green / Blue / Yellow) to a Gen 2 game (Gold / Silver / Crystal) using the Time Capsule feature, they'll often appear holding an item in Gen 2.
Listings state that transferring a Pikachu from Yellow will result in it holding a Light Ball when transferred - a usually very hard to obtain item - and typically the Pikachu partner you start with is the only one you'll find in the game.
However, if I were to trade a different Pikachu over to Yellow (from another Gen 1 game) and then transfer that to GSC, would it be holding a Light Ball, or does it only work for the starter Pikachu? I'm a little loathe to transfer my original Pikachu as whilst I can safely trade it back, trading resets its friendship back to zero. I don't want to upset the little guy!