PokéPark Wii: Pikachu's Adventure doesn't have "secret words"—it has a formal cheat code menu unlocking outfits, music tracks, and bonus content.
Note: Activating cheats may disable leaderboard posting for that save file. Code lists are widely available on GameFAQs, IGN, and Nintendo fan wikis.
Exploration, completing skill games, and befriending all 193 Pokémon reveal hidden items and cutscenes—no codes required.