Or do you mean Cresselia?
After you have beaten the Elite Four(or collected your national Pokedex from Prof. Rowan) use Fly of Surf to get to Canalave City.
Just before the entrance of the gym are houses.
Go into all of the houses until you find a little boy in bed. It is the sailors house.(also has a sign next to it.) Go speak to the little boy then the sailor will come in and talk about a legendary Pokemon called Cresselia.
Go back outside and talk to the sailor again.
He will ask you if you would go to Newmoon island.
Go to new moon island and you will find Cresselia. Click on Cresselia and it will run away, but it has left behind a Lunar Wing! Talk to the sailor to make him take you back to Canalave. Then go back to the sailors house and click on the little boy. He will wake up.
To catch Cresselia, you need a Pokemon that knows Mean Eye. (A Golbat maybe?)
Go to Pokemon Marker Map on your Poketech and walk aroung a bit until a face appears on the map. You will have to track down Cresselia before it moves somewhere else!
When you are in battle you either:
1. Toss a Master Ball if you have one left.
2. Get a fast Zubat/Golbat/Crobat that knows Mean Eye.
3. RUN AWAY!!!
If you chose 2 then use the move Mean Eye and the Cresselia won't be able to flee. Weaken it's health using False Swipe maybe, and then chuck a pokeball at it!
Good luck and hope this helped.
In pokemon Heartgold
No the catch rate is the same in every game
you can certainly catch Dioxies in the game Pokemon pearl
You cannot catch Rayquaza in-game in Pokemon Black.
You cannot catch a tiranitar on any pokemon game, you have to get him from evolving Pupitar.
In which game?
Yes, you can save the game before you catch it. but if you already saved it and the legendary is gone, then you can't catch it. if it is a Pokemon ranger game then you can catch it again
You can't catch a starter Pokemon. But to get all of the starters you can trade the Pokemon to another game and restart the game you were playing and get a different starter.
you catch it in a gba game then catch it in the palpark
You can't catch Mewtwo in-game in Pokemon Diamond.
its been confirmed you can catch it in Pokemon platinum pearl and diamond
Not a real (legal) game.