Level 2: KUMA BRO-OP!!! Activate level 2 and watch as Kuma runs to attack and kill your opponents with his bear hands (get it?), charges, and deadly farts. Very effective in close space stages like Dojo and the first part of Stowaway.
Level 3: SPAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACE Hei-Hichi?-Hiecha-- Karate dude sends his bitches to space. Instakills for 3 kills in FFA, 2 in 2v2.
Notes: ... means you should wait a bit before doing the next attack
a before a move means the move should be done in the air
(meaty) after a move means you have to hit with the last active frames of the attack.
You have to hit so that you hit with the very end of the attack as they're coming out of a roll, landing from AD, or waking up.
Knowing the BnB's can only take you so far, sometimes its more profitable to drop your combo and go for a mixup.
Spinning Demon Starter
Heihachis Spinning Demon Starter(+()()) creates a fantastic 50/50 into throw or an attack due to how advantageous it is on hit. If you grab and they do anything but Jump, they'll be grabbed, on the other hand if you catch their Jump with either +, EWGF, or even + they'll be hit as if they were grounded. If you're successful in hitting the grab or attack you can continue into more resets or go through with the full burst.
Down Tech and Airdodge Traps
Pre 1.12 trying to get a good mixup on someone in the air was insanely difficult due to how safe being in the air was, in combination with the safety of Airdodges and dtechs. Now that these things have been nerfed, many characters including Heihachi can set up some solid mix ups on a recently juggled opponent.
This is setup can be really potent if you know their options afterwards, because if you make a succseful read it can lead into a Burst, another shot at the reset, or even a kill. Generally after this they have Three options: They can Down Tech, they can Neutral tech into Attack, or they can Neutral tech into Airdodge. If you read the Down tech you can either grab them to drain AP or do a meaty + to snag a kill. If they neutral tech you can jump into a+ and it will catch them regardless of whether they attack or AD. Because you have frame advantage you'll stuff out any attack, and be able to throw out another attack before their air dodge ends. This Setup isnt without risk. If they properly read you they can punish you, so make sure to try and force your opponent into profitable habits with safe moves before attempting this.
Heihachi in 2v2 is generally pretty shitty since he has no crowd control, and can struggle to get past walls of spam. That said he has a few gimmicks that potentially may let him decide a match.
Utilizing Kuma Effectively
Kuma is one of the most threatening supers in 2v2, not because of its kill potential but because of the opportunities it affords you and your partner. Kuma lasts for around 8-10 seconds, during that time the enemy team is forced to go on the defensive lest they risk getting killed. This makes them easy to exploit and puts Heihachi's team in a very advantageous position.
Where as before the only option after Kuma was to pursue and help him get kills, now with the addition of the AP drop mechanic, Heihachi can feed his partner AP (relatively)safely while Kuma is out. By building up to just below three Heihachi can feed his partner in the range of 170-190 meter while Kuma is out. This makes Heihachi a fantastic partner to Level 3 oriented characters like Drake, Emmett, Nariko, or Sackboy. The major disadvantage to this strategy is that in general Kuma wont get many kills, since you spend your time feeding your partner as opposed to helping Kuma. However this offset by the fact that you can generally help your partner achieve 3 TWICE since Heihachi builds AP so fast and feeds so well.
Pursuit and Getting Fed
On the flip side since Kuma is in fact a sweeping super, Heihachi can also have his partner feed him to get Kuma sweeps more frequently while the partner picks with 1. Partners that work well this have vertical Level 1's they can get off of Heihachi's Juggles and decent pursuit abilities for Kuma. Examples would be Drake(is there anything he cant do in 2v2?) Sir Dan, Jak, and Radec. Even though Kuma is very unreliable, he is also very very cheap and allows for AP building during the actual super. So even though you may have to rely on Kuma for sweeps you can get him very frequently.
Thanks to patch 1.12 and the AP mechanics changes Raijin grabs now drain 3x the AP or HOLY SHIT A FULL BAR. Successfully landing one against the enemy team can decide a match since will it rob them of 100-300 AP and give that right back to you. If Heihachi lands a grab on the other teams sweeper it can be very, very hard for them to recover. Don't think they're completely out of the question due to being telegraphed. Kuma, your partners three, or even your partners normal attacks can help set it up. Raijin grabs may not land often but it can and will happen, and when it does it can be devastating.
Other Moves of Interest
EWGF is great for getting past walls of spam and is one of his only real options for doing so.
Heihachis Level 1 while being out shined by Kuma is still a useful super. It only costs 100 AP and since Heihachi eats AP like Fatty P eats cake he can easily make it back. Not to mention it can potentially be better for feeding than even Kuma since if you snag a double kill you can feed your partner 50-100 AP before they respawn. Just use it sparingly, outside of the low cost it has no redeeming features and if you fail you flush 100 AP down the toilet.