Professor Juniper is a Supporter card from the *Black & White* set. Its effect reads:
"Draw 7 cards. Then, discard your hand."
This ability effectively lets you shuffle your discard pile into your deck and draw 7 fresh cards, effectively allowing you to retrieve any Trainers you may have discarded.
There are other cards that can help you retrieve Trainers from your discard pile, but they usually have specific requirements or limitations. Here are a few examples:
* "Professor Sycamore": This Supporter card allows you to draw 7 cards, but it requires you to have no cards in your hand.
* "N": This Supporter card lets you draw cards until you have 6 in your hand, and then your opponent draws cards until they have 6 in their hand. This can help you to retrieve Trainers from your discard pile, but it's not as direct as Professor Juniper.
* "Pokémon Fan Club": This Item card allows you to search your discard pile for a Trainer card and put it into your hand, but you can only use it once per turn.
Ultimately, Professor Juniper is the most reliable and efficient way to retrieve Trainers from your discard pile.