Where and Tips to Catch the Legendarys - Guide for Pokemon Platinum

NOTE: These are in order on how easy they are to Catch.

~Rotom~
Level 2o in the old Chateu. It is in the TV upstairs and ONLY at night.
I Suggest you use Dusk, Nest or Ultra Balls for Quickest Capture.

~Azelf~
Level 50 in the Lake Valor Cavern. Go to Lake Valor and surf to the middle of 
the lake where there is a cave entrance.
I used Ultra Balls and cought it in 4 turns, you could also use Dusk balls.

~Uzie~
Level 50 in the lake Acuity Cavern. Go to Lake Acuity and Surf to the Middle of 
the lake where there should be a Cave Entrance.
I used a Quick ball and Cought it but you should use Ultra and Dusk balls, too.

~Regigigas~ Level 1 in the Snowpoint Temple.
You should weaken it with a Level 2-4 Starly, Shinx or Budew and then use Nest 
Balls.

~Dialga/Palkia~ Both are level 70 and at the Spear Pillar. First you need to 
get the Lustorous and Adamant orbs from the Waterfalls cave in Mt. Coronet, 
than go see the elder in the retirement Building in Celestic Town. 
I used a Quick ball on Dialga and Caught it and an Ultra Ball on Palkia. You 
should use Dusk balls, Net Balls(Palkia) and Ultra Balls to Catch them.

~Giratina~ Level 47 in Distortion world/Turnback cave.
During the story, you go to distortion world with Cynthia, Cyrus and the lake 
Pokemon. At the end, you battle cyrus and than Battle Giratina. Use Ultra Balls 
to capture it. If you KO or Run from Giratina in the Distortion world, Go to 
Turnback cave and find Giratina in there.

~Heatran~ Level 50 in Stark Mountain.
After helping Buck Defeat team Galactic go tothe battleground in the Survival 
area and return to the place where Charron was defeated, Heatran should be 
there now.
I suggest using ultra and timer balls on it.

~Mesprit~ Level 50 and in lake Verity Cavern. Go to lake verity and surf to the 
middle where there is a cave entrance. Whene you talk to it, it dissapears and 
you have to Chase it around Sinnoh. Use Mean look on it and use ultra balls to 
capture it.

~Cressilia~ Level 50 and on fullmoon island. Go to full moon island and find 
it. Talk to it and it will dissapaer. Chase it around Sinnoh and try to capture 
it. This is a good time to use the masterball, since Cressilia has a Cthch rate 
of 9/250.

NOTE: All of these except Dialga, Palkia, Heatran, Regigigas and Cresselia can 
be found before elite four.

Bonus Action Replay pokemon: Darkrai.
Level ? and Newmoon island. Turn Walk anywhere on on your action replay and go 
to newmoon island. Keep going East till you get to an island. You should be on 
newmoon island. Go in the forest to see Darkrai. Talk to it and you will be in 
a battle with it.
I suggest you use Ultra balls or Timer balls on it.