If your return to the Sinnoh region in Pokémon Brilliant Diamond and Pokémon Shining Pearl is not nostalgic enough for you, then you may want to get your hands on the DS Sounds key item.
After conquering the Elite Four and entering yourself and your battle-hardened Pokémon team into the Hall of Fame, to acquire it you will need to return to the Hotel Grand Lake resort at Valor Lakefront. You can either Fly to Pastoria City or Veilstone City before making your way along Route 213 or Route 214 to reach it.
Once you are at Valor Lakefront, the building that you will need to enter is at the top of the resort. You can see the screenshot below for a quick visual pointer, but, from what we can tell from our own exploration, it’s the only accommodation that has a swimming pool outside of it – if that makes locating it easier.
Inside this building, there is a Gengar-loving Game Director, a Psyduck-obsessed Game Director and a Sound Designer wielding a guitar stood near a bed. You will want to speak to the Sound Designer, who, after realising that you have beaten the Sinnoh Champion, will reward you with “something cool” for your achievement.
That reward is the DS Sounds key item, which is described as “a music player that allows you to listen to nostalgic songs. It’s operated with the flip of a single switch.” Whenever it is activated from your Bag, the game’s audio is replaced with the soundtrack and Pokémon cries from the original Nintendo DS games which were first released in Japan way back in 2006.
Pokémon Brilliant Diamond and Pokémon Shining Pearl are now available exclusively for Nintendo Switch worldwide.