As Tim and Pikachu tour the GNN Building at the beginning of Chapter 6, one of the hosts of show called Maximum Music, Olga, will approach Tim and Pikachu about her missing Purguly. Near the End of their tour, directly before rehearsal for the show is set to begin, Olga will still not be able to Find Purugly. Of course, Tim and Pikachu will quickly be put on the Case.
By talking with all of the Pokemon and people found within GNN, you will eventually Find Purugly within Magnemite's cage found in one of the dressing rooms. Once you have found Purugly, you will then be tasked with finding where Magnemite went off to. In order to find Magnemite, you will have to talk with Hiro and learn about the interference he has been receiving. Using Yanma, you will then be able to see what area is picking up the most interference, as this is where Magnemite will be found. After finding both Purugly and Magnemite, your tour of GNN will End and rehearsal will begin.