How to Get a Shiny Pokemon in Pokemon Black 2
General Information
The reason I put these two games into a separate entry is because of the introduction of two new Key Items that made a permanent stay in the franchise. These items are the Shiny Charm and the Oval Charm!
https://m.bulbapedia.bulbagarden.net/wiki/Shiny_Charm
https://m.bulbapedia.bulbagarden.net/wiki/Oval_Charm
The Shiny Charm increases your odds to find a shiny Pokémon! Your odds go from the standard 1 in 8,192 to a glorious 1 in 2,731! The Oval Charm increases the likelihood of an egg appearing in the Daycare. These are both Key Items, so you cannot trade them to a different game or collect multiple of them to further increase your odds. You need to complete the National Pokédex to get the shiny charm(not including Mythicals) and you need to complete the Unova Pokédex to get the oval charm(not including Mythicals) Keep in mind that you cannot turn off the Shiny Charm after receiving it and everything you find afterwards is no longer considered a full odds shiny; it will be considered a method hunt shiny.
Fun Fact! If you happen to catch a shiny Kyurem and want to fuse it with regular Reshiram or regular Zekrom, the fusion will still appear shiny! You don't need to have a shiny Reshiram or shiny Zekrom for the fusion.
Shiny Hunting Methods
1. Random Encountering
https://forums.somethingawful.com/showthread.php?threadid=3767823&pagenumber=4
Same as Black and White. If you can encounter it, it can be shiny(unless it's Shiny Locked of course). You can still find shiny Pokémon in Phenomenon encounters. Illuminate increases your likelihood of wild encounters happening if you have a Pokémon with this ability in the front of your party. Patrat and Watchog are two Pokémon that can have the Illuminate ability.
2. Soft Resetting
To soft reset in these games you need to hold down L, R, Start, and Select at the same time. The starters are now given to you by Bianca. No battle this time, so you can just check it's summary after picking the one you want. Other than the starters, you can soft reset for the Unova legendaries(except for Zekrom and Reshiram), fossil Pokémon, Volcarona in the Relic Castle, and the Zen mode Darmanitan outside of the Relic Castle. Black 2 and White 2 actually added a handful of older legendaries. These include Regirock, Regice, Registeel, Regigas, Uxie, Azelf, Mesprit, Cresselia, Heatran, Latios(Black 2) and Latias(White 2), all of which you can soft reset for. Roaming legendaries are a little more annoying to hunt. Once you encounter a roaming legendary for the first time, the game does one shiny roll and sticks with it for the entirety of that Pokémon's existence. This means that you're going to have to save to a point before a roamed gets released into the wild to roam and then soft reset back to that point to start the encounter over again. Don't worry! If the roamer appears shiny and then runs away from you, it will still be shiny when you go to encounter it in the grass again. Make sure to save to lock the roaming legendary into being shiny and good luck catching it.
3. Dark Grass(also known as Double Grass)
https://m.youtube.com/watch?v=bk6UPwEjq5Y
The darker patches of grass within the Unova region will sometimes let you encounter two Pokémon at the same time. The game automatically pulls out the first two Pokémon in your party to help even out the playing field. You have full control over both of your Pokémon and you can waste a turn switching one of the Pokémon out or using an item if you don't want to risk attacking a shiny. You can only catch one of the two Pokémon you encounter, so you have to knockout the one you don't want. The Shiny Charm does help you get more shiny rolls while doing encounters in the dark grass.
4. Breeding
Odds with the Masuda Method is still 1 in 1,365, but now it's combinable with the Shiny Charm! If you have a Shiny Charm while doing the Masuda Method your odds become 1 in 1,024. Masuda Method is when you breed two Pokémon(within the same egg group) from two different countries of origin to increase your chances of hatching a shiny Pokémon. It's a little harder to pull off now since the online features are no longer supported by Nintendo and you have to jump through hoops to use it again, but it's still worth the mention. Of course you don't have to use the Masuda Method to hatch a shiny, it just increases your chances. Without doing the Masuda Method your shiny chances would be the same odds as wild Pokémon. Having a Pokémon with the ability Flame Body or Magma Armor in your party as you hatch eggs will help speed up the hatching process. Litwick/Lampent/Chandelure can have this as one of their abilities. You can find Litwick in the Celestial Tower. Breeding a shiny Pokémon does not make it more common to hatch a shiny and you cannot hatch the same egg over and over until it becomes a shiny. Once an egg is generated, it's already determined if it's going to be shiny or not, so you have to continuously hatch eggs until one becomes a shiny.
***Background is by angemons on tumblr. This is the original post of the background***
How to Get a Shiny Pokemon in Pokemon Black 2
Source: https://aminoapps.com/c/pokemon/page/item/shiny-hunting-in-black2-and-white2/8GhX_I8n0kP8NqPXWeZNkmDgVVKQQ2