NO! That is just a myth.
There is no legendary Pokemon in Undella Bay.
None. You find the artifacts for money to sell to the maniac in Undella City. YOu can also find 14 of the plates in here to use for arceus.
you can get him at route 13, undella town (in the water of course), and undella bay
You can't catch arceus in pokemon white.
undella bay
no arceus isn't in Pokemon white cause arceus is in sinnoh not unova hope this helped sorry you cant get arceus :D
In Undella Town
at Undella town a girl will give it to you
Undella Bay
Yes, she has a house in Undella town.
You can get Walrein at Undella Bay in the winter.
you can get arceus on Pokemon white only if you get arceus on Pokemon platinum and do poke transfer.