Pokémon Platinum Version (Italian) - Catching Mesprit

After your quest at the Distortion World, return to Lake Verity and go into its cavern. After you interact with Mesprit, it will ward off and roam all over the Sinnoh region. Use the Marking Map on the Pokétch to track the areas of roaming Pokémon. Once you’re at the area where a boss symbol is marked, you’ll encounter the roaming Pokémon. Mesprit is on Level 50. Remember, roaming Pokémon flee on the first turn. If you still have the Master Ball, it would be the time to use it. Otherwise, have a Pokémon that knows Mean Look then use Dusk Balls when battling at night.