Blocking is an integral action to keep yourself alive. Knowing how to use which block in which situation will improve your game immeasurably. Not only will you be able to defend better and survive longer, but in some cases you will be able to resume your offense faster.
Basic ground blocking is the most common defensive option. To guard against high attacks, simply hold . To guard against mid attacks, hold or . To guard against low attacks, hold . If you guard incorrectly, a "Guard Break!" message appears on the side of the screen.
After blocking S Normal attacks, you can immediately cancel into Homing Dash and Z Reflect. This is also true for some moves that can be super dashed through, such as Beerus's Cataclysmic Orbs and Piccolo's Homing Energy Blast.
Remember, you cannot block Dragon Rushes and throws!
Basic air blocking is even easier; simply hold any backwards direction while airborne. Air blocking does not have high/low blocking, but instead come with the restriction that you suffer more blockstun than ground blocking (6 more frames to be precise), which will likely force you to the ground while giving the opponent even more frame advantage.
Also remember that after you air block (any kind), your jump options are restored! This means that you can do something like double jump to block an aerial projectile, then double jump again, or airdash afterwards, if you're not too close to ground.
As with ground blocking, you also can't air block against air Dragon Rush and air throws.
Z Reflect is a defensive tool that puts the character in a defensive stance that will block both highs and lows, and lose to Dragon Rush and throws. On a successful reflect, you will recover sooner than normal. If you reflect a physical strike, then you will stay in place while pushing the opponent away. Reflecting a projectile will keep you in place.
Breaking Dragon Rush
When the opponent catches you with a Dragon Rush, press L/M/H between 4 frames before the hit until 4 frames after the hit to break the rush (total 9F: 4F before + the frame it hits + 4F after).
Also if two Dragon Rushes meet each other, it is automatically broken.
On Dragon Rush break, both players break away from each other and recover full screen away. While you can act while airborne, ground Dragon Rush Breaks remove you air options until you touch the ground. Air Dragon Rush Break does not restore your air options.
Hold A1/A2 or press +A1/A2 to swap out your point character with another on your team. After using a Z Change, you cannot use your teammates for anything else for a short time. Following that, there's a cooldown on using the character that was called back for a Z Assist or another Z Change. Cooldown will not commence while the opponent is in stun, but will continue if it has already commenced.
You can perform Z Change while in a neutral state or any time you could perform a special cancel. Players often cancel into Z Change after hitting the opponent with 5H or 2H since that allows players to safely change in a new character while extending the combo.
You can not perform Z Change while blocking or while in proximity block animation.
Guard Cancel Change / Guard Cancel
When ground blocking, press +A1/A2 to swap out your point character with another on your team at the cost of 1 Ki Gauge. On hit, the opponent is knocked away. On block, you cannot act and are fully punishable. As with a Z Change, you are locked out of using the character you tagged out for a short period of time. If you are down to one character, you will cancel into an attack that teleports behind the opponent instead, similar to a Vanish, only much slower and with some forward movement after the teleport. This version cannot be canceled into a Vanish, unlike off a Change.