Question: Who was the most powerful witch in charmed?
Disambiguated questions and answers: question: Who was the most powerful witch in charmed as youngest sister?
Who was the most powerful witch in charmed as middle sister?
Who was the most powerful witch in charmed as eldest sister?
answer: Phoebe Halliwell
Piper Halliwell
Prudence "Prue" Halliwell
Prue Halliwell
Natural Questions answer: Prue (from the Wikipedia article "Prue Halliwell")