Pokemon White 2 Challenge Mode FAQ:

Q. What is Challenge Mode? 
A. Exclusive to B2W2 is the Key System. Upon completing the game, you are awarded keys that 'unlock' the option to let you change the difficulty of the game. In Black 2 you unlock Challenge mode, and White 2 you unlock Easy mode. After you have obtained these keys, you can transfer them between carts using the IR built into the cartridges. So, I transferred a Challenge Mode Key to White 2 from Black 2 and will try to beat the whole game on Challenge Mode.

Q. What changes in Challenge Mode?
A. The only thing that changes are the fights. Most landmark fights (Gym Leaders and Elite Four) get an extra Poke, as well as better movesets, held items, IVs, abilities, etc. In general these fights range from mildly annoying to worse in comparison to their Normal Mode counterparts. Most regular trainer fight ranges just vanish.

Q. Which fights are the worse?
A. Elesa /terrible/, Cheren is just spam Ember and pray you live, Burgh can just own you with multi-hit Rock Blast, Clay can troll you with Bulldoze/Explosion, Marlon is still annoying, should I continue?

Q. What are you playing on?
A. A OGDS (phat) with a capture board installed from: https://3dscapture.com

Q. What is RNG Manipulation?
A. RNG Manipulation allows me to get perfect stats on my Pokes, this is crucial for a run where all the notable trainers you have to fight have beefed up IVs/Movesets. Broadly speaking, RNG is seeded by you r DS Mac Address, what buttons you hold on game launch, what date/time you launch the game, the game you are playing (B/W/B2/W2) and timer0. The Mac Address being part of the equation means that everyone must come up with their own manipulations (unless you multiple people run using the same console). 


Q. What is Timer0?
A. You don't want to know, but its annoying and slightly inconsistent in White 2. Changing your DS Parameters (Nickname, Color Theme, Pictochat comment, GBA game/Option Pak inserted, etc.) along with Auto Mode can make it consistent (our knowledge on /how/ they influence timer0 is unknown, so typically you just keep messing with them and testing to see what seed you hit and if it comes from the right timer0. It's as big of a pain as it sounds.)

Q. What do you manipulate in the game?
A. We manipulate a Rash Tepig with good stats (its the best by far for the early game), and extend that manip to get a Pidove and Psyduck for Fly/Surf/Strength, the three HMs we need to beat the game. When we get to Castelia, we manipulate a Perfect 5IV Drilbur w/ Adamant nature out of Relic Path to main the rest of the game. I will also do one more manip shortly after Marlon to spawn two phenomenon and skip 2 trainers. known as Trainer Skip.

Q. What is Trainer Skip?
A. Trainer skip involves using RNG manip to spawn phenomenon in front of trainers' vision so mandatory trainers become skippable. Phenomenon are the shaking grass, rippling water, shadow spots, etc. that you may see in the overworld in Unova. Trainers cannot see through them. We use this to skip 2 trainers, a male swimmer on Route 21 and a ranger in Seaside Cave. This saves 13-19 seconds if executed correctly (you will lose time if you only skip the swimmer). 
 
A video demonstration of the skip: https://youtu.be/hYVKKzdSe18
 
Q. How do dust clouds spawn?
A. You probably didn't ask that but I will answer it anyway. Dust clouds have a 10% to appear every 20 steps. The cloud can spawn anywhere in an 11x11 grid centered around the player that is considered valid. This grid is split into 4 11x6 "quadrants". The game will first pick which quadrant to spawn the cloud in, then gather a list of all the available tiles, starting from the top left of the quadrant to the bottom right going left-to-right. Then the game picks a random number between 1 and the number of "valid" tiles and will spawn the phenomenon on that tile. The logic is the same regardless of the type of phenomenon. Phenomenon do not count tiles that have things such as trainers on them as invalid, but will stop the cloud from spawning under a trainer's feet if it detects something on it. NPCs can also delete clouds by walking over them. 

Q. Why do you not name Tepig?
A. It isn't work it due to how fast text moves in Gen 5, and for how little we use Tepig/Pignite. We will nickname Drilbur.

Q. Why Drilbur?
A. Excadril is a very strong Pokemon in Gen V, and basically wipes everything in the game. There aren't many Pokes that can even get close to Excadril's power and movepool, which is especially helpful since Drilbur/Excadril get access to Hone Claws and Swords Dance, which is extremely crucial in a game where X items are not available until very late in the game. However, Drilbur is a shit poke, so the section where we do not have Excadril yet is one of the most reset heavy (especially in Challenge Mode).

Q. Why do you nickname your Drilbur 1/2/3/x?
A. I tend to nickname my Drilbur based on how many balls it took to catch it. So first ball gets 1, 2nd ball gets 2, etc. Unless I'm lazy in which case I will nickname it '9' because it's right next to the OK button,