Uxie, Mesprit and Azelf
Uxie, Mesprit, and Azelf - much like the Beast trio in Generation II - are well-known for being roaming Pokémon seen in Generations IV and V of Pokémon; but, again, they’ll spawn one of the three once per day from a Mirage Spot in an instant battle.
To begin, it seems that the base condition is to simply have three Pokémon with maximized Happiness on your active team: Pokémon you have kept alongside you for the majority of the game (such as your starter) should adequately work out for this.
When three such Pokémon are in your party, begin Soaring and a Mirage Spot, "Nameless Cavern", should appear in the area around Sootopolis City. Which Pokémon you encounter seems to be affected by the time of day. Here are the estimates:
- **Uxie** : Found between 8:00 PM and 9:00 PM (a time interval of one hour)
- **Mesprit** : Found between 9:00 PM and 4:00 AM (a time interval of seven hours)
- **Azelf** : Found between 4:00 AM and 8:00 PM (a time interval of sixteen hours)
Dialga and Palkia
Dialga and Palkia are two Pokémon found in Pokémon Diamond, Pearl, and Platinum: they are the god-like Pokémon created by Arceus at the start of the universe, and they govern time and space respectively.
Much like a ton of legendary Pokémon in this section, they’ll be found through Mirage Spots, though you’ll find only Palkia in Omega Ruby and Dialga in Alpha Sapphire.
To begin finding them, you’ll have to have all three of Azelf, Uxie, and Mesprit in your party when you begin to Soar; once done, go south of Dewford Town to find a rip in the spacetime continuum. Approach and enter the tear to find the Pokémon.
Giratina is the complement to the trio containing Dialga and Palkia, being the focus of Pokémon Platinum: it is one of the three Pokémon Arceus created to govern the world, but it was sent to the Distortion Dimension for its recklessly violent behavior.
Finding it is very much akin to Dialga/Palkia - Soar south of Dewford Town with both Dialga and Palkia in your party and you’ll find another tear in space that you can enter to find Giratina.
Heatran can be found after you beat the Elite Four for the first time. To begin, head to Route 120, to the east of Fortree City. There, go east along the southern portion of the Route and downstairs when you can; Surf south from there into the cave, the Scorched Slab.
As you enter the Scorched Slab, you’ll be able to meet with Flannery, who is looking for a certain Pokémon here. This Pokémon is Heatran, and can be found at the very end of the dungeon; if you want a walkthrough see the Feather Badge chapter.
Now, as we understand it, the continuation of the Regi quest, much as in Pokémon Diamond, Pearl, and Platinum, involves the three Regi Pokémon you recently found and hopefully caught: Regirock, Regice, and Registeel.
Regigigas is more or less the ruler over the three, and also can be caught in this game. You need the following:
- The three Pokémon just named (Regirock, Regice, and Registeel) - they must be caught on Omega Ruby or Alpha Sapphire
- Regice must be nicknamed - it doesn't matter what it is nicknamed to, so long as it is nicknamed
- Regice must be holding a Never-Melt Ice item - Try and trade one from somewhere.
Offensively, Regigigas won’t be much of a worry during the first few turns, as Slow Start will halve his Attack and Speed, so try to be quick about this.
Cresselia is much the opponent to the Event Pokémon Darkrai in various Sinnoh-region lore, as has been exemplified several times throughout the core series games, the Pokémon Mystery Dungeon series, and the Pokémon anime and manga.
Unlike Darkrai, Cresselia was very easy to obtain in Pokémon Diamond, Pearl, and Platinum, relatively speaking, being more or less a set event like a Legendary Pokémon battle. The same can be said for its appearance in Black 2 and White 2.
Finding Cresselia isn’t too bad here either, being found at random possibly once daily or being brought over through StreetPass. If found, it will be on an island named "Crescent Isle" (much as in Diamond/Pearl) southeast of the Hoenn region, between Routes 128 and 129.