What is the walk through walls cheat yellow?

hold down a and b at the same time then turn around to face pikachu, whilst holding down a and b continue holding down a and b and tap select three times you will walk through pikachu and through the wall behind him hold down a and b at the same time then turn around to face pikachu, whilst holding down a and b continue holding down a and b and tap select three times you will walk through pikachu and through the wall behind him