Steps (expanded items pack setup)
1) Get the expanded items pack with a TM04 somewhere in the bag.2) Go to the first floor of Celadon Department store, and select the TM04, then swap it with the 33rd item (it should always be above a HM04, which is just like putting CC in map address D35D. At the leftmost tile of the exit mat there should be a Full Restore below the HM04, too.
3) You'll be taken to the continue/new game/option screen with the department store music still playing. Press B to see blind Pikachu. If you select a new game, the palettes will be wrong until the end of the intro.
Note: TM05, Antidote, TM06 and TM31 also work