2.X is one of those odd mechanics that new players frequently ask a lot about, and it'd be helpful to have an all-in-one place to answer all of those questions. If anyone needs to ask about 2.X, direct them here!
What is 2.X?
2.X is the collective term used for 2-controller playstyles. The reason these are used is because the 2nd controller can be used during opening (and ending) cutscenes in every level, which can be beneficial. Most prominently, you can hold forward with the 2nd controller and watch enough of the opening cutscene in order to build acceleration for your "running boost" and start the level in full speed. This saves approximately 0.35s, and we're getting to the point in The Elite where that amount is significant enough to make many WRs and even untieds much easier to achieve.
2.X also allows a player to open doors, switch weapons, and fire with the A, B, and Z buttons. On Caverns, you can open the lift door in front of you before the level starts, and on Depot SA/00A, you can blow up the screen in the mainframe room, which also alerts guards to open the door.
Both controllers can use A and B as normal, but each of the 4 control styles mix up what Z and the controller stick does.
2.1: 1st - Move/Fire, 2nd - Look/Aim
2.2: 1st - Look/Fire, 2nd - Move/Aim
2.3: 1st - Move/Aim, 2nd - Look/Fire
2.4: 1st - Look/Aim, 2nd - Move/Fire
Because 2.X is generally used for starting in full speed, 2.2 and 2.4 are the most common 2.X control styles, while 2.1 and 2.3 are never used. 2.4 is used for Depot SA/00A and other levels where you want to shoot, and 2.2 is generally used when shooting isn't necessary.
In the opening cutscene, your weapon is initially set to "null", which is different than Unarmed, so you need to switch twice to use a gun. Mines, Grenades, and other projectile weapons are not loaded when used with 2.X and are useless.
2.X during opening cutscenes does not work in Perfect Dark.
How do I use 2.X?
There are two types of 2.X: automatic and manual. Automatic is when you can set the 2nd controller aside, cruise-controlled (L+R+Start to set your controller stick's neutral position) into top-left/right and then held with a rubberband, which is useful on some levels where you only strafe one way for the entire level (such as Streets and Caverns A). Manual 2.X is when you physically operate both controllers for levels where you're making strafe changes. For manual 2.X, cruise-control the 2nd controller stick downward to have the neutral position interpreted as forward.
Anyone and any controller can make use of automatic 2.X, but manual 2.X requires some player skill and ideally a certain type of controller stick. Stock N64 controller sticks have poor range, even when cruise-controlled, and you can occasionally lose full speed while changing strafe directions. Most players use a Gamecube-style replacement controller stick for their 2.X controller, which is far more sensitive and easier to use. They eliminate the possible loss in full speed when circling from top-left to top-right and vice-versa. Some players also use Superpads and other sensitive controller sticks for their 2.X controller.
When you physically hold the two controllers, you'll ideally want to have left thumb on the 1st controller stick, left index on the 1st Z, right thumb on the 2nd controller stick, right middle on 2nd Z, and right index on 2nd A and B. If you prefer moving with your left-hand, you could also swap the controllers. I also suggest playing with both controllers on your lap and tilted downward and inward for good ergonomics and not straining your wrists. Some players also prefer having the two controllers physically conjoined with tape.
Manual 2.X is awkward to use at first, but becomes easier over time. I strongly recommend learning 1.2 before 2.X if you're brand new to the game so that you can develop your movement before complicating it.
What levels use 2.X?
The majority of levels can make use of 2.X, though are dependent on personal skill level with the control style. Almost everyone uses 2.X on the simple, basic levels, but the more technical and difficult levels are only used by true masters. Here's a brief overview of using 2.X on each level:
Dam A - Very easy level and 2.X helps save a lot of the time to get down to the next second. This is one of the best levels to learn 2.X on.
Dam SA - Needing to stop in place and backup for the alarms makes 2.X extremely difficult to use without losing time, since you also can't cruise-control it.
Dam 00A - Because of the pause for the Covert Modem, 2.X for the initial part of the level can be useful, but completions on fast-paced runs can be difficult to be worthwhile.
Facility A/SA/00A - Despite crouching at the start of the level, this is a forced crouch, so you don't lose full speed. However, watching cinema with 2.X can complicate the open door strategy. Reserved for 2.X masters.
Runway A/SA - Easy level with 2.X and significantly helps for getting 0:22.
Runway 00A - 2.X can be used for the Tank strat if you're fairly technical, or the old Grenade strat, but you cannot R-lean with 2.X.
Surface 1 A - Your pace is mostly dictated by your locks, and stopping in place is a little awkward, but 2.X can help cover for sub-optimal lines and movement.
Surface 1 SA/00A - A good intermediate challenge for 2.X. The level is quite long, but the actual movements aren't too complicated. If you're confident with your skill and want to develop further with 2.X, I strongly suggest using it here.
Bunker 1 A - Not useful since you can't reach the door and the quickpause kills full speed anyway.
Bunker 1 SA/00A - You can alert a guard to open some doors behind you, but given the rate of completion on these two levels, it's not recommended to go for that strat, which makes 2.X not useful.
Silo A/SA/00A - Very challenging and can allow for differently timed door cycles if you're good at the level. 00A is actually the easiest to use 2.X on because of the pause for the Plastique early in the level, but may negatively affect door cycles. On PAL and Jap, you can alert a guard during the satellite cutscene, but is unknown if it's useful at all and most likely just creates unnecessary lag.
Frigate A/SA/00A - While Frigate has many spots where we pause and the speed benefit can be nice, especially on Agent, the rate of completion is low enough to not warrant using 2.X because of the time that would be spent switching control styles all the time. During the opening cutscene facing the bridge of the ship, you can kill the bridge taker with 2.3 because you can tilt your aim. However, it's essentially random if guards and/or objects will be loaded and you'll most likely end up blowing everything up and creating lag. Overall, I recommend not using 2.X on Frigate at all.
Surface 2 A/SA - You can't R-lean with 2.X. 2.X is very helpful for older strats though since the level is simple.
Surface 2 00A - The level is quite long and you need to do some precise shooting, so 2.X isn't very helpful here and you'll likely just lose the 0.35s time save through worse movement and aim. I don't recommend using it here.
Bunker 2 A/SA/00A - Not useful since we pause immediately.
Statue A/SA/00A - While the movement throughout the level is simple, Val strafing with 2.X is quite tricky. The time saved is fairly significant for a long, basic level however, so if you're talented with 2.X, it's very helpful to use it here.
Archives A/SA/00A - Not only do you start in full speed, but you can slap earlier too. These two combined save a lot of time, but the level is somewhat technical for 2.X. 0:16 is easy enough with 1.2 and is a great level to develop your skill level, so I would actually suggest doing it with 1.2. If you're keen to learn 2.X though, you could use it instead, or after achieving 0:16 with 1.2.
Streets A/SA/00A - You can use automatic 2.X here, so there is no reason at all to use 1.2. For Streets SA and 00A, you can switch to 1.2 as you meet Valentin.
Depot A - If you're playing for 0:26, I suggest using 1.2 because of the learning potential, though 2.X does make it significantly easier. If you're going for the warp strat, you can use automatic 2.X and play all in left-strafe. If you're technical you could also potentially use 2.4 to blow up the screen, lure out a guard, and get a rare boost.
Depot SA/00A - 2.4 is required here to make full usage of 2.X. By blowing up the screen, you partially complete one of the objectives, as well as killing a guard, and luring two out to open the door. This level has the greatest time save with 2.X and is essentially mandatory.
Train A/SA/00A - You can switch to the Watch Laser in the opening cutscene to save on a laggy switch, as well as blowing up a box and guard, but you need to be a 2.X god to do the brakes.
Jungle A/SA/00A - The movement is fairly simple, but the throws and careful aim can be difficult with 2.X. It's a fairly intermediate level overall compared to some others, but I wouldn't recommend 2.X here unless you're very good with it. You could theoretically use automatic 2.X on Agent, but it's more difficult than what it would be worth.
Control A - Full speed helps with getting a door warp, as well as moving a bit faster, but getting a run started is hard enough. I don't recommend it unless you're going for WR or 3:57 or so. You can also lure a guard or blow up the big screen, but they're both not useful.
Control SA/00A - Because we shoot the drone immediately in the beginning, 2.X isn't useful.
Caverns A/SA/00A - 2.X allows for both full speed and also opening the lift door. For Agent, you can use automatic 2.X, though you still need to press B on the 2nd controller. SA and 00A both get the nice time saver too, but are complex levels to be using 2.X on. Only for pros!
Cradle A/SA/00A - Because we're capped with Trev's speed, 2.X doesn't really help at all.
Aztec A/SA/00A - You can create enough noise in the beginning to alert the first room guards to get an early AR33 on top of full speed. Only recommended for Agent though because you'll most likely die on SA and 00A. Technical note: auto-aim does work during the opening cutscene. You can also lure out the big room laser guard, but is not recommended since he gets in the way while going for a glass strat and causes some lag (though useful on LTK and DLTK).
Egypt A/SA/00A - Movement is mostly simple here, so Egypt is a great intermediate level for 2.X. If you're also using the crouch strat for the door before the first Baron, you can't cruise-control your controller stick.
Closing
Hopefully that covers everything you'll need to know about 2.X! If you have any additional questions or corrections for this guide, let me know and I'll update it!
