Ultimate Custom Night Guides:
The Vent Crawlers
The first step in beating 50/20 is knowing which animatronics you need to worry about, and which ones you don't, so as to be able to focus on as many things as possible. Let's figure out how to economize your power and hone your reaction time in order to beat this intimidating mode.
The five vent crawlers (Mangle, W. Chica, Springtap, Ennard, M. Freddy) are a great place to start when conserving your time and power. In fact, they don't have to be worried about hardly at all. Since you don't have the time to watch them through the cameras, just close the vent door whenever you flip up your camera, and open it again when your camera is lowered. Sorted!
The Duct Crawlers
The five duct crawlers (Happy Frog, Mr. Hippo, Nedd Bear, Pigpatch, Orville Elephant) are even easier to handle, unless you're unlucky. Placing an audio distraction in front of the left air duct should distract most of the animatronics and repel the others. You can usually only afford the time to look at the ducts once, which is why it's important to make sure that one time keeps all of the five in check. Sadly, this is one of the luck-based parts, as Orville may be able to bypass the audio distraction and get inside. Try to switch to the duct camera and place the audio distraction in under a second, to save as much time and power as possible.
The Plush Animatronics
The three plush animatronics (Nightmare Bonnie, Nightmare Mangle, Circus Baby) are fairly easy to handle as well\. Each of them only appears once per night, but watching them on the cameras will prevent them from getting inside. This is why you need to be able to keep your camera on the East Hall at ALL TIMES when one of them appears, so do everything on the other cameras that you need to do as quickly as possible, and then switch to the East Hall Camera and keep it trained there for the rest of the night.
The Side-Vent Animatronics
The three side-vent animatronics (BB, JJ, Afton) can all be blocked off by using the Side-Vent Door, and will appear very often on higher difficulties (excluding Afton, who only appears once). Blocking them with the Vent Door is very useful for farming Faz-Coins for paying Rockstar Freddy and the Death Coin. BB and JJ can both be seen in the vent doorway, and won't enter until you flip up the monitor again. Afton will make large clanging noises, and then enter soon after.
The Flashlight Animatronics
The three flashlight animatronics (P. Freddy, N. Freddy, N. BB) can all be kept at bay by using the flashlight provided to you. Shining on Phantom Freddy until he dissapears completely will make him stay away longer, saving power. You will also need to quickly register whether Phantom BB is standing up or slumped over, preferably under 1/2 a second, and then shine your light on him if he's standing.
The Misc Office Animatronics
The other eleven animatronics that appear in the office (Nightmarionne, Rockstar Freddy, Rockstar Foxy, Rockstar Bonnie, Scrap Baby, Bonnet, Minireenas, RXQ, Lolbit, N. Chica, Withered Golden Freddy) are a little harder to deal with, due to their diverse mechanics. If you want to deal with them, try to register which of them are active and require attention, and which don't, as quickly as possible. Then try to deal with as many of them at a time as possible (For Example: putting on the Freddy mask to deal with W. Golden Freddy and Toy Bonnie, whilst keeping your mouse away from Nightmarionne and shining your light on P. Freddy), so as to take care of them as quickly as possible. Dealing with as many at a time efficiently is one of the most important elements in 50/20, so focus most of your practice on handling several animatronics at a time in order to beat it.
The Doorway Animatronics
The five animatronics that appear in the Doorways (Freddy, Rockstar Chica, N. Fredbear, Nightmare, Ballora (as well as the Plush Animatronics, but I already mentioned them)) are a problem as well. Freddy gives no audio/visual cue when he approaches the doorway, forcing you to either check on him through the cameras or test closing the door every now and then to keep him at bay. Jack-O-Chica doesn't need to be worried about as long as you keep the office relatively cool (below 90 degrees), and Ballora can be taken care of as long as you're listening for music in either hallway. However, Rockstar Chica can pose a problem, due to not having any audio/visual cues. For the animatronics like Freddy & Rockstar Chica, the best way to defend against them is closing the left doorway whenever you enter the camera system, and opening it again after you've closed the camera. Make sure that the wet floor sign is on the right of the room to take care of Rockstar Chica. Also be sure to quickly check both doorways for N. Fredbear and Nightmare.
The Cove Animatronics
The four cove animatronics (Foxy, Bonnie, Funtime Foxy, Plushtrap) are some of the animatronics you need to spend most of your camera power on. You'll need to quickly register which figurine is on the desk (Foxy or Bonnie), and check the cove if Foxy is there. You'll also need to check the other Pirate Cove curtain near the beginning of the round to see what Funtime Foxy's showtime is, preferably under 2/3 a second, and quickly dispatch Plushtrap if you see him by the Pirate Cove curtain. However, if you use the Death Coin on Funtime Foxy this will save a lot of brainpower and time.
The Kitchen Animatronics
The two kitchen animatronics (Chica, Marionette) are manageable if you know what you're doing. You can't afford the time to check on the Kitchen frequently to wind up the music box, so use the Global Music Box to calm the Marionette down instead. (Try the following pattern to conserve power: Wait 12 seconds, turn on Global Music Box, Wait 18 seconds, turn off Global Music Box, rinse and repeat). Note that the Music Box takes about 16.5 seconds to wind down completely, and about 18.5 seconds to rewind completely by using the Global Music Box. The Global Music Box will take care of The Marionette, Chica, & Lefty.
The Distraction Animatronics
The eight distraction animatronics (P. Mangle, P. Balloon Boy, OMC, Trash And The Gang, Helpy, El Chip, Funtime Chica, Phone Guy) are only in the game to distract and confuse you, as well as sometimes making auditory disturbances and triggering sound-sensitive animatronics. The two Phantoms can be easily managed as long as you don't spend too much time on the cameras, and keeping your fingers handy for pressing C and Enter will also take care of El Chip & Old Man Consequences. Helpy & Phone Guy can be easily dispatched if you click on them fast enough, but Trash And The Gang & Funtime Chica are completely unavoideable. Try to take care of them as quickly as possible, as you need time to focus on more lethal animatronics.
The Sensitivity Animatronics
The three sensitivity animatronics (Jack-O-Chica, Music Man, Lefty) will attack you if the noise or heat gets too high, but can easily be handled if you keep the temperature and noise levels fairly low. This can be difficult at times, as it forces you to keep an eye on your noise and heat levels and respond accordingly, whilst handling all of the other animatronics. Lefty doesn't need to be worried about if you're using the Global Music Box.
You may be wondering why Toy Freddy has his own section in this guide. #1: His mechanics are so different from the others he should have his own group, and #2: He can be an EXTREME pain when attempting 50/20. This is because he needs to be checked frequently to make sure he hasn't lost his game, and is the cause of most of the jumpscares for people attempting 50/20 (excluding Nightmarionne). The only real way to handle him is to check him on the monitor as soon as you start the game, close the appropriate door on his game, and pray that he doesn't jumpscare you (because after this you will be using all your camera time on the East Hallway).
Trust me, this is one of the ONLY ways you'll be able to beat 50/20 legitimitely. A big problem with the mode is that it's mostly luck based, meaning no matter how good you are, there's still a high chance you'll lose (kind of like Solitaire). Just follow these instructions and pray that you don't get shrekt by some of the luck-based animatronics!
Start by turning on the power generator and turning off your fan. Next, flip up the monitor, switch to Toy Freddy's cam and close the correct door on his game, then place an audio lure in front of the left air duct (make sure the right air duct is closed). After this, switch your camera to the East Hall (for the Plush Animatronics), and flip down your monitor. Then, move the Wet Floor Sign to the right doorway, and take care of any animatronics in your office that require attention. Then check the Global Music box (try to keep the Power Generator on for about 10 seconds, then the Global Music box for 20; paying attention to it will take care of The Marionette, Chica, and Lefty). Flip your monitor up and down on the East Hall Cam as often as possible for a bit to keep Foxy (and some others) from moving right away, and make sure to close the left doorway and the middle vent whenever you flip up your monitor anywhere past 30 seconds in the game. As soon as you have accumulated 10 Fazcoins, purchase a Death Coin from the Prize Counter and use it on Funtime Foxy, then switch back to the East Hall Cam. Make sure to pay attention to the office temperature (turn the fan back on when it reaches 80-85 degrees). After this, everything is based on luck. Just make sure to keep your eyes and ears open for any animatronics that require attention, and make sure to turn on/off the Global Music Box and Fan whenever you have to. At this point, you just have to hope that you won't get killed by some of the luck-based animatronics (Orville Elephant, Toy Freddy, etc). Follow these steps and you should be pretty well off at beating this insanely difficult mode!