I would think the Champion would be common knowledge to the general populace in the Pokemon world. Kinda like in the anime, everyone knows who Cynthia is because she's the champion. Ergo, if Sycamore is the champion, it should be known relatively early in the game.
4e is not D&D, but WoW making a Disguise check. Pokemon Black Friend Code: 0605-2800-9952; Trainer Name: Solace; First Pokemon (roleplaying): Snivy (Monty)