This event occurs when you take a special Celebi to the Shrine in the Ilex Forest. You’ll time travel and you even get to meet and battle the Rocket Boss Giovanni. EDIT: Why so many comments about sending money to your mom in the past? Have you guys not realized that the battle with Giovanni occurred during the present (or during the Rocket Takeover of the Radio Tower) and not three years in the past? Before Commenting: Please don’t ask how I got a specific Pokemon. This is only for demonstration purposes so don’t go “OMG YOU CHEATER ST00PD!!” or “UBER USER” or whatever.