Love Hurts - S1-E21
Corrected entry: In this episode when Piper says the power switching spell so that she can heal Leo it switches not only her and Leo's powers, but also, Prue's and Phoebe's; however in future seasons it only affects the witches it is meant to. (00:19:00)
Love Hurts - S1-E21
Corrected entry: After the darklighter takes Daisy, Phoebe suggests switching powers back would be faster, Leo says it would take too long. In the time it takes Leo to coach Piper and help her locate Daisy, they could have switched powers, Leo could have located her, and orbed them all to Daisy.
Correction: Leo states that he is still too weak to use his powers which is why it would take longer if they switched powers back.
Correction: The first time the power switching spell was used, all of the sisters were in the room when it was cast, thus all their powers got swapped. But in the future episode this post is referring to (it specifies episodes plural, but the only other episode this spell was used in is "Ordinary Witches" from season 7) Piper and Phoebe were the only ones home when they did the spell so it didn't affect anyone else. Furthermore, in the first episode the spell was used, Prue also swapped powers with a Dark-lighter and simply had Phoebe cover her ears so as to not be affected by the spell, implying that one needs to actually hear the spell for it to have any effect.