Finding and catching the Legendary Psychic-type Pokémon Cresselia is one of the end-game activities in Pokémon Brilliant Diamond & Shining Pearl. Cresselia is one of the many Legendary Pokémon that was included in the original Pokémon Diamond & Pearl, and it makes a return to the Sinnoh region in the faithful generation IV remakes. Although Cresselia was first introduced in Diamond in Pearl, it wasn't obtainable until players received the National Dex after discovering all Pokémon that were native to the Sinnoh Pokédex.
Unlike most mainline Pokémon games, Diamond and Pearl featured quite a few Pokémon, like Cresselia, that weren't originally part of the Sinnoh Pokédex even though they were introduced in this generation. Nonetheless, getting the National Dex in Pokémon BDSP is an easy task provided players play through the entire game and speak with every NPC they come across. There are several Pokémon that are harder to come across naturally, like Drifloon and the opposite version's legendary exclusive, which is why it's important to interact with every NPC in Brilliant Diamond and Shining Pearl.
After receiving the National Dex players need to head to the Pokétch company headquarters in Jubilife City to receive the Marking Map app for the Pokétch. Speak with the President of the company on the first floor and he'll install the application on the Pokétch. The Marking Map allows players to automatically track Pokémon that will run away after a battle begins. Like Mesprit in Pokémon Brilliant Diamond and Shining Pearl, Cresselia is a Pokémon that will roam around the Sinnoh region and run away from battles if it isn't stopped as soon as the battle begins. Fortunately, there are a handful of Pokémon that can prevent Cresselia from escaping the battle, but trainers can always use their only Master Ball to catch it immediately.
Cresselia Location in Pokémon Brilliant Diamond & Shining Pearl
From Jubilife City, head to Canalave City and enter the house just before the sailor's boat. This is the same sailor who brought players to Iron Island earlier in the game, where they worked with Riley and received the Riolu egg in Pokémon BDSP. The house there is his home, and his child is stuck in a nightmare. Speak with both the child and the mother, then return outside and speak with the sailor. He'll explain that he needs the Lunar Feather, which is only accessible on Fullmoon Island.
After reaching Full Moon Island players will encounter Cresselia, which immediately flees and leaves behind the Lunar Feather. Pick up the Lunar Feather and return to the sailor and sail back to Sinnoh. Re-enter his home and use the Lunar Feather on the son to wake him up. After seeing his son awake, the sailor will allow the trainer to sail to other islands once more. This doesn't need to be completed before catching Cresselia, but it's required in order to catch Darkrai in Pokémon BDSP once the event is available in-game.
Once Cresselia begins roaming around Sinnoh, trainers will need to manipulate its travel path for a short while in order to get it to align with the trainers' location. Head to any location that is adjacent to a route with tall grass, and run back and forth between the two areas until Cresselia is in the same location as the trainer on the Marking Map app. Like Mesprit, Cresselia's location changes on the Marking Map app every time players enter a new location in Pokémon Brilliant Diamond and Shining Pearl. Getting Cresselia to be in the same location can take any amount of time, though most likely it will not take more than 15 minutes.
Trainers have a few different choices as they try to capture Cresselia, with the easiest being the Master Ball method in Pokémon BDSP. By far the most challenging way to capture Cresselia is by throwing a Poké Ball at it every time it is encountered since Cresselia will run away after the first move of every battle. Players can also attempt to damage Cresselia every time they see it, and because Cresselia is a singular encounter it will retain the same amount of HP it had when it fled the battle. Additionally, Cresselia will also retain any status affliction like paralysis or poison. However, if players are looking to catch Cresselia with a Poké Ball of their choice, they'll have to put a little more work into weakening Cresselia in a single battle.
How To Catch Cresselia With Any Poké Ball In Pokémon BDSP
Catching Cresselia with any type of Poké Ball can be done more easily if players have an Umbreon in Pokémon BDSP with the right moves. First, trainers will have to speak with Bebe to receive an Eevee after acquiring the National Dex. Bebe is in Hearthome City in the home next to the Pokémon Center, and she'll give players an Eevee after a short conversation. After receiving Eevee, increase its friendship and level it up at night to evolve it into Umbreon. Alternatively, players can catch an Eevee in the Trophy Garden after acquiring the National Dex.
Next, level Umbreon to level 50 so it can learn the move Mean Look. Using Mean Look will prevent Cresselia from being able to run away, making Cresselia easier to catch in Pokémon BDSP, so long as Umbreon doesn't faint. Additionally, Umbreon will need to be at a high enough level to outspeed Cresselia in order to use Mean Look, but an item like the Quick Claw can help give Umbreon a chance to outspeed Cresselia.
Umbreon's type advantage and incredibly high defense stats should allow it to take a few hits from Cresselia before it's in danger of fainting. Furthermore, Umbreon's low attack power will allow it to slowly chip away at Cresselia's health with a move like Quick Attack, bringing it down to an ideal state to capture. Umbreon can also learn moves like Flash and Double Team to lower Cresselia's accuracy and raise its own evasiveness, respectively, allowing it to endure the battle longer.
Since Umbreon cannot learn a status move without breeding an egg, leading with Pikachu, Magneton, or any other Pokémon that can use an obvious move like Thunder Wave. Use Thunder Wave on Cresselia, let it run away, find it once more leading this time with Umbreon, and apply the aforementioned Mean Look, Flash, Double Team, and attack strategy to weaken Cresselia. Capture Cresselia more easily in this weakened state with any Poké Ball in Brilliant Diamond and Shining Pearl.
Pokémon Brilliant Diamond & Shining Pearl is available now on Nintendo Switch.