This guide was taken off of pastebin. It was made by the fine @Novasonicrun on twitter (you rock).
If corrections are due and you need me to edit/delete the guide, please message me on discord (SAUZ#9999).

NOTE:
The info here IS outdated in many aspects because this was made a while back, but overall most of the info here is still good. Realistically, this guide serves only to exist until a new (better) one is posted.

The best fighting game.

-F2 restarts the game, this can be done in any menu.
-In the bootup screen, press 2 on your keyboard to switch to English menus.
-Press Spacebar to enter the control config.
-On your gamepad, press left or right to make that controller apply to player 1 or 2, respectively.
-Keyboard cannot be mapped to player 2.
-Press up and down to scroll through the controller config, and press A to map a button.
-There's also an auto button config and a button test feature.
NOTE: as the controls change, the commands for controlling this menu also change
A: Light attack
B: Heavy attack
X: Special attack
Y: Ultra EX attack (supers)
XY: EX Special attack. This is a shortcut button. It's highly recommended that you use it.
Start: Pausing, quitting from character select.
Back: Taunt
The two options below that are record and replay for use in training mode.
Highlight the bottom option and press A. The game will begin.

On the title screen, you can change the game speed. Most of the time, stick with 2 stars, the default. The game is fast enough as it is. The option appears to be somewhat unstable, in any case.
In the options menu, you can change the resolution, volume, FPS counter, etc.
Fullscreen is not available in the current version.
DO NOT EVER ENABLE THE VSYNC OPTION. EVER! The framerate will become extremely unstable. This option will be removed in the next update if it can't be improved.
You'll notice the FPS counter might jump a lot between 59-60, even on powerful machines that should be able to run the game flawlessly. This is normal.

A more in-depth (still not perfect) guide exists online for this right here.
https://docs.google.com/document/d/1dXKP6KXaApfU0TfoVCxPem2vB21OfHarJEbRems-1kU/edit

Anyway, here's the original pastebin text.
Hosting a lobby requires you to open a port on your router. This process can vary slightly per router, so do some research on Google. Also remember to allow the application to connect to the internet through Windows. You may need to put in an exception in your firewall.
The host of the lobby will experience no lag. It kinda sucks, but that's just how it is. Sorry, I don't like it either.

DAMAGE IS ♥♥♥♥♥♥♥ NUCLEAR.
You can pick 1, 2, or 3 characters. The more characters you have, the less HP each has.
You can pick between 2 different supers per character. Make note of the input when you select it.
There are no special move inputs. Attacks are only standing, crouching, and jumping variations of each button.
No attacks can be canceled into any other attacks. All combos are link combos.
There is an infinite input buffer. During any animation, hold down the input of the attack you want to do next and you will do that attack on the first possible frame. This works out of blockstun and hitstun as well.
Fighters can walk right through each other. They can occupy the same space, no problem.
DAMAGE IS ♥♥♥♥♥♥♥ NUCLEAR.
Throws are performed with B in close range, but do have some startup and can be jumped.
You only gain meter when hitting the opponent, parrying, or walking with Ultra EX Type (more on types in a bit).
Parries and red parries exist, just like SF3. Tap forward just before recieving damage. You must parry lows with a down input, and a low parry cannot parry anything else. Parrying multihit physical strikes and multihit projectiles has a different timing. You can parry in the air with either forward or down. Parry inputs have a cooldown, and they can be seen underneath your lifebar in training mode.
EX Specials cost 50% of one bar, and they're well worth it.
Every EX Special in the game has invulnerability, even the ones that probably shouldn't. Some have more invulnerability than others.
If you hit the enemy when the EX indicator at the top of the screen flashes, you get lots of free meter.
You can slightly change your position during wakeup.
The Boko Boko gauge is a guard gauge with some twists. The gauge does NOT recover during a round, and it also goes up a little if you get counterhit. When it fills, you will be dizzy, and the next hit you take will have amplified damage. You're almost certainly dead if this happens.
DAMAGE IS ♥♥♥♥♥♥♥ NUCLEAR.

Similar to the groove or -ism systems, types slightly or drastically change effective strategies. You pick type separately for each character, though nothing stops you from using the same type multiple times.
-Stamina (red): Get more HP. This can be quite useful for characters that already have above average HP, or if you're playing a team with only 1 or 2 characters.
-Speed (blue): Have a faster movement speed. This does not affect your attack speed. Use this if you want to play a more effective and unpredictable footsies/spacing game, but love your character's Ultra EX too much to want to pick the next listed type...
-Super (gray): Have both benefits of Stamina and Speed, but lose the ability to perform your character's Ultra EX. This is most recommended if you rarely ever use your character's Ultra EX attack.
-Ultra EX (green): Gain super gauge whenever you walk forward, and rather quickly at that. Not having enough meter to do an EX Special often spells doom, so use this if you love those Ultra EX attacks and EX specials!
-Demon (yellow): Lose the ability to perform your character's Ultra EX, but in exchange, get a sort of "max mode" activation that allows you to spam EX Specials for a limited time. Allows for some very silly combos and nearly unstoppable invulnerable rushdown with some characters while it is active.
-Abnormal (pink): You can't guard, but every time you hit the opponent or make them guard, you heal a bit. You still retain the ability to parry. The usefulness of this type greatly varies by character.

If your opponent doesn't have enough meter to do an EX Special, go on the offensive.
Damaging and difficult combos can be quite situational, so don't be dead set on doing them. Focus on the damage you can get from playing smart.
DAMAGE IN THIS GAME IS NUCLEAR, so never give up! You can always make a comeback, no matter what!
Attempting to punish a reversal EX Special is generally not a good idea, as even the punishable ones can recover too quickly for you to realize it, and they might be able to throw out another and counterhit you! If your character has a projectile, try using that instead of going in with a melee attack.
Solid reliable anti-airs are hard to come by. If you're not willing to spend meter, it can be better to go for an air to air if you smell a jump coming your way.
Escaping pressure without meter is VERY difficult. Jumping out of the corner is more viable than it is in most fighting games, especially since the opponent reacting to the air hit with an effective juggle requires great reactions and awareness.
Because throws have a bit of startup, using them in a dangerous situation when the opponent has approached you is a very poor idea. Only use them when you have them scared of your attacks.
Every character has at least one attack that changes their aerial trajectory in some way. Use it to stay unpredictable!

Press and hold A+B on the same frame. If no attack comes out, you have activated throw storage. Continue to hold A+B. You can move your character around and they will throw once they enter the throw range, but you lose the ability to guard during this state. It is particularly useful for tick throws. You can do a jump in on block, buffer into throw storage, and not have to worry about timing.
Considering there are a few frames of tick throw protection, the few frames of throw startup, and the fact that reversals are so strong, this bug was actually deemed as not damaging to the game. It was intentionally never fixed. So get used to it!