Arceus is only in the game as a statue ( The statue is not Arceus )
Arceus is not in Explorers of Time or Explorers of Darkness. There is an Arceus statue in Explorers of Sky, but there is no real Arceus that will join your team.
No, Arceus does not appear in the game in-person, there is a statue of it in Destiny Tower, and his power is alluded to in the last of the Special Episodes.
In Pokémon Mystery Dungeon: Explorers of Time and Explorers of Darkness, players obtain Arceus by completing a special mission called "Defeat Arceus!" in a post-game location known as Destiny Tower. The mission is unlocked after reaching a high floor in the dungeon and requires a strong team to defeat Arceus in battle. Once defeated, Arceus will join your team as a recruitable Pokémon.
Gordon?
Defeat Darkrai then cresselia will be outside your house talk to her she will join your team.
yes
defeat him 2
arceus garitina darkria groudon dragonite
You can't recruit Arceus, but you can find an Arceus statue on the 100th floor of Destiny Tower along with the item Space Globe, which doubles your attack. You can unlock Destiny Tower at Spinda's Juice Bar randomly by drinking beverages after you graduate from the Guild.
Defeat him at spacial rift then go back there and beat him a second time he will join your team probably.
It doesn't necessarily join on the first time. On my explorers of time he it didn't but on my explorers of sky it did. It's all to do with Giratina's recruit rate (about 8.6%)
Do they have to ask you to join or can you let them join by doing something