Once you've gone through the majority of the storyline, you can find it at Lake Acuity. (Snowpoint City)
You meet them at each lake and battle them until you get all the way to each of the caverns.
in snowpoint twileaf and pastoria near them or the blue things on the map
After beating Cyrus on Mt. Coronet, surf to the caverns on the the three lakes. You can catch Uxie and Azelf here. When you meet Mesprit, it will flee. You will then have to run all around Sinnoh to catch it, and it will move if you fly. Hope that helps.
after you save the three of them from team galactic, go to the cavern and see mesprit. it will leave. It will now rome around the region and you have to track it down using the poketch app "marking map" and catch it in the grass with the normal wild pokemon.
yes you can. I've tried to catch mesprit but instead I caught Uxie in the Aucurity cavern and Azelf in valor lake front where team galactic was. It's really easy just decrease the HP as low as possible and I used a dusk ball. when the ball glows yellow rub the screen with the pen in the ds as hard (but not to hard) and as fast as possible. If you have more Pokemon questions just ask me and next time give me you're code so I can register you. Theres you're answer!
Team Galactic's Boss' name is Cyrus.
You find it in the Galactic Headquarters after they capture Azelf, Uxie, and Mesprit.
When you save Azelf, Mesprit and Uxie in Vermilon City. (Team Galactic HQ) It goes to one of the lakes in Sinnoh region.
After this you go to the top of mount coronet...assuming you have rock climb...There you face Charon, Dialga, Palkia are there and i believe this is where you enter the distortion world to capture Giratina...
You go to the team galactic base and beat the three commanders and release mesprit, azelf, and uxie and you get a masterball. You can also get first place in the lottery.
in snowpoint twileaf and pastoria near them or the blue things on the map
After you defeat Cyrus at the spear pillar, you can go to the lakes and defeat Uxie, Azelf and Mesprit.
I'm thinking your talking about Diamond or Pearl, you must wait for the event with Team Galactic (if that's there name).They will capture them all and you'll to release them. Azelf and Uxie will stay in their cave, but Mesprit will run and you'll need to find it in various places.
If you are talking about getting him to appear to obtain the Warehouse Key, you must complete start and follow the storyline about saving the legendary Pokemon of Lakes Verity, Valor, and Acuity (Mesprit, Azelf, and Uxie) from the hands of Team Galactic.
you have to navigate your way through the galactic HQ in veilstone city. at the end you will warp to some creepy rooms with creepy green tubes. then go through the hall and you will find a door, which is where uxie, mesprit, and azelf are sealed in these chamber thingies. you must talk to Saturn and he will battle you. after you defeat him, he will tell you to press the button and set uxie, mesprit, and azelf free.
sorry, it is imposible.azelf, mesprit and uxie are from dimond, pearl and platinam. blue rescue team was made way bifor thees games
After Uxie, Azelf, and Mesprit get captured by Team Galactic, go to Veilstone City and go to the Galactic Headquarters. When you try to get to the Headquarters, a grunt will drop a key. Go to the warehouse to the west. Once you get through the building, you will fight Cyrus, the Master. He will babble about emotions and power and then he will give the Master Ball to you. Then you have to beat Saturn to get Uxie, Mesprit, and Azelf out of the jail. Alternatively, you can get multiple Master Balls by winning the lottery in the Jubilife TV Station, although the odds are very, very low.
there is one in veilstone city and eterna city. i think of mt. coronet once you get to go to Dialga. there is a LOT of grunts there. i hope i help you. btw i need help getting Azelf, Mesprit and Uxie. i dont have dusk balls.