Cobalion, Terrakion and Virizion
Cobalion, Terrakion, and Virizion make up the primary three members of the "Musketeer" group of Pokémon from Generation V, often paired alongside Keldeo, the "unofficial Musketeer" of the group much as D’Artagnan was in The Three Musketeers.
As with the previous sets of three Pokémon in one Mirage Spot, you’ll randomly encounter one of the three per day until you’ve gotten them all. To be able to activate the Mirage Spot, have three Pokémon with maxed EVs on your active team.
You can tell a Pokémon has maxed EVs when the gauge to the right of the Super Training app is full and there’s a muscle-man icon in the top-left corner. Additionally, that Pokémon will be able to play the Secret Super Training rounds. Not really hard if you’ve been using them since early on.
The Mirage Spot, "Pathless Plain", should appear south of Route 131, in the general vicinity of Pacifidlog Town on one of the random islands to its south. You will only be able to encounter one of these per day:
- **Cobalion** : Sunday, Wednesday, or Friday
- **Terrakion** : Tuesday or Saturday
- **Virizion** : Monday or Thursday
Tornadus and Thundurus
Tornadus and Thundurus are two Pokémon that are part of the Therian trio in the Pokémon Black/White games: a conflict rose between them in Unova before being quelled by Landorus, who you can also find through Mirage Spots.
They are known as the Therian trio mostly because you can get a Reveal Mirror to transform them into their Therian Forme; you’ll initially find them in their Incarnate Forme, but the Reveal Glass changes that. To get the Reveal Glass, take any one Pokémon of the trio to the mirror shop in Mauville.
As for finding the Pokémon themselves? For this, you’ll need to put Castform into your party and begin Soaring; a thunderstorm will appear in the area near Fortree City. Approach there and opt to enter it. Therein, you’ll find Tornadus in Omega Ruby, or Thundurus in Alpha Sapphire.
Landorus is the third Pokémon of the Therian trio in Pokémon Black/White, and it played a role akin to that of Rayquaza: that is, it quelled the conflict between Tornadus and Thundurus.
Much like those two, Landorus is initially found in its Incarnate Forme, but it is possible to change it to its Therian Forme by the same method: bring it, Thundurus, or Tornadus to the mirror shop in Mauville, then use the earned Reveal Glass to change it.
In order to find Landorus, you’ll simply need to Soar with both Tornadus and Thundurus in the party and then you’ll find another thunderstorm above Fortree which you can enter.
Reshiram and Zekrom
Reshiram and Zekrom are the Pokémon who were the focus of the Pokémon Black/White games, representing truth and idealism respectively. They and Kyurem are said to have been one Pokémon in the past as well.
In any case, at least you don’t have to play a DS game to find these Pokémon now, though note that Reshiram is exclusive to Pokémon Omega Ruby and Zekrom to Pokémon Alpha Sapphire.
More importantly, however, it is now possible for Reshiram and Zekrom to be legitimately Shiny ! You can soft-reset as desired to attempt to get a Shiny version of these Pokémon, although the odds are still against you (1 in 4096 without the Shiny Charm, and 3 in 4096 with).
In any case, the condition to activate the Mirage Spot is to have a Level 100 Pokémon on your team; any Level 100 will do, even if you traded it or imported from the Bank or something like that.
Soar with said Pokémon and you’ll be able to find the "Fabled Cave" Mirage Spot in the area north of Route 134, in the whereabouts of Slateport City and Route 110.
Kyurem is like the brother to Reshiram and Zekrom, and was the focus of the Pokémon Black/White 2 games, in particular with his ability to fuse with either one of them to create a powerful Pokémon; this ability takes its root from the Unovan lore in which the three were once one Pokémon.
Anyway, to be able to find Kyurem, Soar with both Reshiram and Zekrom on your team and you should find the Mirage Spot "Gnarled Den" north of Mt. Chimney, in the general vicinity of Routes 113 and 114 and Fallarbor Town.
When you enter the cavern, be sure to use the Dowsing Machine in order to find the DNA Splicers !
The DNA Splicers is a key item which allows you to fuse Kyurem with Reshiram (forming Kyurem-White, a powerful Special-attacker) or Kyurem with Zekrom (forming Kyurem-Black, a powerful Physical-attacker). This is very important as Kyurem sucks otherwise.