I am going to share all I could gather until now about Squall. The first fact you need to keep in mind is: Scrubs can't win with Squall. "What is that supposed to mean?" you might say, well, it means you CAN'T SPAM BULLSHIT OR PRESS CIRCLE CIRCLE SQUARE TO WIN MOTHER F****. AHEM! Well, let's start showing Squall's strong and weak points:
Medium/High bravery damage attacks
Fast bravery attacks
Dodge punishing HP attacks
Thrash Exdeath and Emperor
Large advantage over easy to punish melee chars
Good ground game with a reliable forced HP link (Thunder Barret --> Blasting Zone)
Doesn't have advantages over the most used melee chars of the game
Doesn't have a viable HP link in the air (Fire Barret --> Rough Divide or Aerial Circle won't land 90% of the time)
Can't cover dodges
Easy to punish HP attacks
His attacks don't allow blodging, blocking or using other attack right after they are used (except Fire Barret)
No long range attack
Now, the abilities:
Should Always Be Equipped on Squall
Ground Dash (for ground assist build, good against characters that stay mostly in the air) or Omni Ground Dash + (good to avoid attacks on the ground and punish them with thunder barret)
Free Air Dash
Free Air Dash Boost
Assist Gauge Up Dash
Speed Boost ++
Jump Times Boost +
Ground Evasion Boost (it doesn't make Solid Barrel --> Upper Blues harder by the way)
Midair Evasion Boost
Descent Speed Boost
Jump Boost ++
You can use ones without pluses to save CP for Achy+ for example. Jump boosts are good when you need to avoid attacks or keep a minimmun distance (Beat Fang doesn't require you to be too close to your oppenent after all) without the risk of getting dodge punishes. They are a must for turtle tactics.
Always Target Indicator
EX Core Lock On
Assist Lock On
Note: DO NOT EQUIP AUTO ASSIST LOCK ON, it doesn't have any benefits for Squall.
Should Always Be Equipped on Squall
Assist Critical Boost (I don't recommend this one if Yuna is your assist)
Disable Counterattack/Sneak Attack
Exp to HP/Assist
Back to the Wall
Disable Riposte (good VS Exdeath)
Master Abilities that increase HP (Guardsman) or BRV (Machine, Protector, Best Dresser)
Revolver Drive (may become less useful in stages or chars that force air game)
Fated Circle (I really don't recommend this one, BUT, it helps in a very specific situation, when you land thunder barret and want to follow with a HP, if the oppenent has two assist bars and spend them during your HP attack, you may lock his assist without getting staggered like you would be with Blasting Zone, it also has a chance of counting as two hp hits to get double depletion and/or double Side By Side effect)
Techniques and Tips
Lock off Beat Fang (useful to build assist after dodges without going to the opponent's direction)
Lock off Aerial Circle (useful to use the absorb effect without going to the oppenent's direction when its not necessary, very nice against Ultemecia, just be careful with the assist punishes if you don't have two assist bars and the opponent has one)
Beat Fang dodge punish (you won't survive not doing it)
Aerial Circle/Rough Divide/Blasting Zone dodge punish (RISKY)
Dash Feint (useful to keep yourself in place, pressuring and building assist)
Blodge --> Aerial Circle (this may turn the tables)
Revolver Drive to avoid Aerith Holy and Exdeath's Maelstrom
After a block, if you are not going to break, ALWAYS USE AERIAL CIRCLE
Check the amount of ex force around the stage, opponent's assist bar and bravery, Thunder Barret --> Solid Barrel --> Chase --> HP can be more rewarding than Thunder Barret --> HP (use it to reduce the ex force absorption of the opponent, specially if he is using a Aerith --> Chase whore like Prishe and Lightning. Thunder Barret --> HP is always more rewarding if you are running a Side By Side build and if you are not going to break with Solid Barrel, keep that in mind)
Circle the opponent with jump within the range of Beat Fang to prevent assist building
Assist: Advantages and Techniques
Kuja: he lets you do the following things as Squall, besides his great capability of punishing and dealing damage:
On the ground, right before Kuja's multiple holy hits with Snatch Blow (position yourself right above the opponent within a resonable height), you can land Aerial Circle with ground rush AND another Aerial Circle (dodge cancel and wait a little until you press X in this case, you can even position yourself close enough so you don't have to press X) for triple or fourfold depletion OR a full critical Beat Fang (if you attack fast enough). You can also use Heel Crush and then Aerial Circle or Beat Fang. Use him after a ground rush.
In the air he lets you do one Aerial Circle OR one Rough Divide OR one Beat Fang, choose the HP that will cause a wall rush, use Beat Fang for a break only. Summon Kuja after a wall rush or before Beat Fang ends or even during stagger caused by Fire Barret (the distance won't matter, since you can teleport).
Yuna: useful when you want to reduce risks of having your assist locked
She sucks if the opponent is on the ground, BUT, all Squall's ground moves takes the opponent to the air, so you can combo with Shiva making Yuna a great choice for Squall.
With the right timing, you can get double depletion (even triple counting wall rush) with Aerial Circle a little before Shiva's last attack. Use Yuna right after the third hit of Beat Fang and neutral dodge during the assist summon sequence, then use Aerial Circle.
Yuna combo with Solid Barrel before the thrusts allowing another Solid Barrel or any ground HP including Revolver Drive for massive damage and ex generation (thus the need of Solid Barrel --> Chase sometimes, unless you got Heavens Cloud weapon with Tenacious Attacker red accessory)
Yuna can also combo before the last hit of Upper Blues in the air, back dodge to fall faster and use the options showed in number three, if there is almost no ground bellow, use Aerial Circle during Yuna's attack, its safer.
Other viable (and not as good) options: Emperor, Aerith, Jecht.
Don't guarantee win but make a large difference sometimes, most of these builds require CP Glitch (AKA Labyrinth Bug). Small changes are always welcome depending on your gameplay:
The Wicked Anti-Exdeath Build
Notes: equip Grounded instead of Aerial in Order's Sanctuary, since the cores appear on the ground in that stage; Jump Boosts and Master Guardsman helps
The Reckless Damage Build (182 defense)
Notes: opitional non Side By Side accessory build, for example, instead of Empty Ex Gauge and Side By Side, put multipliers like HP<=50%, Large Gap in HP, Aerial or Dismay Shock; remove Booster if you intend fighting in the air and put Aerial in its place; opitional Machinery (+100 BRV) extra ability.
The Safe Build (185 defense)
Notes: opitional - exchange Adamant Chains with Judgement of Lufenia (shield, helm, armor), exchange Lionheart with Earthbreaker, exchange damage accessories with multipliers, exchange Hyper Ring with Dragonfly Orb, exchange Rebelious Soul and many other possibilities; Adamant Chains with Precision Evasion may be handy against Sephiroth's Shadow Flare spam.
The Standard Build (Ex core absortion emphasis)
Notes: I basecly use Seal of Lufenia to get rid of Dismay Shock, but if you think you really need ex depletion, feel free to equip it; you can exchange Lionheart with Earthbreaker and/or put Side by Side accessory build for example.
Fight Fire with Fire Build (If you are not sure you can grab the cores; you can get two assist bars when you hit the opponent's assist with Aerial Circle thanks to Side by Side)
Notes: USE IT ONLY AGAINST A CHAR YOU ARE ABSOLUTELY SURE THAT WILL USE SIDE BY SIDE (recommended against Zidane, Golbez, Firion and Onion Knight); the equipment gives good stats (179 attack and 184 defense), you may want to use with other accessory builds.
The Ex Force Build
This build doesn't offer good defense and attack: 182 and 177 respectively. You can try using judgement of lufenia set for 184 defense and ridiculous 176 attack on a character that is not a linker, that means you need to hit like ten times more than you get hit to have a chance to win depending on the matchup. At least you don't have to worry about opponent's ex bar using this build.
The Experimental Defense Build (186 def)
I dont know any uses of it, but its there just for you to know that is possible to get all that defense.
Final note: if you noticed, I gave five different useful builds with different pieces of equipment, that means, you may want to keep the equipment in each of the five sets and just change the accessory as you see fit, without having the work of doing CP Glitch over and over.
Extra: My Build
I wanted something that could increase the hitconfirm power as much as possible, so I currently run this build. Yuna just in case the opponent has 2 bars of assist. 1265 Bravery, 179 attack, 183 defense, +80% physical damage.