Answer:
To get the notched ear Pichu, you must have a special Pikachu coloured Pichu first from the 12th movie. He has to be the first one in your party. Once you have dont that, go to the shrine in Ilex forest. When you go to the shrine, the notch ear pichu will appear from behind the shrine. It will start to play with your pichu, then a man will appear and talk to you. After he is done talking, you will obtain the notch ear pichu. It is female, level 30, and cannot be used in any trades.