NGBC2's engine mechanics

Buttons:
A - light kick
B - heavy kick
X - light punch
Y - heavy punch
C - extra button 1 (function varies depending on the character)
Z - extra button 2 (function varies depending on the character)
S (start) - taunt (a few characters have an effect that come with their taunts. What the effect is depends on the character)
*Note: both Rick and Rolf do not use the B button.

Tag team commands:
*character switch - push C and Z at the same time to switch characters. Your characters have invincibility when leaving the screen, but they are not invincible when entering. Tagged characters will gradually but very slowly recover health indefinitely until they are tagged back in.
*team attack - hold down, then push C and Z at the same time. A full super meter is required for this, and the effect/damage of the attack varies greatly from character to character. Some team attacks are greatly damaging while others are weaker but serve a more tactical purpose.

Directional commands:
*tap forward twice - run/dash (whether or not dashing or running occurs depends on the character)
*tap back twice - backdash
*up/up-forward/up-back - jump (some characters can short-jump and/or super-jump (tap down, then up/up-forward/up-back)
*hold back/down-back when attacked - blocking
*hold back when attacked in the air - air blocking

Recovery commands:
*air reversal - this is where you perform an attack immediately after air recovery, or after you recover from an hit in the air that doesn't knock down. Depending on the situation, air reversals aren't always possible.
*safe fall - when falling, push A and X at the same time just as you hit the ground. (some moves are not possible to safe fall from)
*air recovery - when knocked into the air, push A and X at the same time while you are in midair. It isn't always possible to air recover depending on the situation, and the longer your opponent's recovery time is (for the move that he/she just used to knock you into the air), the longer it takes before you can air recover.
This prevents a lot of rather useful moves from being rendered practically useless - otherwise, the opponent would be able to air recover almost instantly (like in older builds of NGBC2) and punish you during your recovery time. (what's the point of having good moves if you're just going to get punished for using them even though they connect? Hence, the time it takes to air recover = the opponent's recovery time.)
All characters can air recover except Kim, Vince (aka Clark) and Chris - they have their own automatic air recovery system in place that helps them defend against most attacks.

Wakeup commands:
*quick wakeup - rapidly tap any of the attack/directional buttons after getting knocked down
*delayed wakeup - do not press any attack/directional buttons after getting knocked down
*wakeup roll - hold either forward or back after getting knocked down (only certain characters can do this)