Alternate Guard
Originally a bug, and now back in KOF XIII as a feature is a technique called Alternate Guard. If you are in blockstun, you can extend your blockstun by quickly alternating between low and high block (i.e. by wiggling 
~ 
~ ~ ). The reason why you would want to do this is because you can extend the time that you are invulnerable to being thrown. Alternate Guard is therefore a great way of avoiding tick throws and can allow one to subsequently punish the whiffed throw. Video
The best way to learn this skill is to get the timing in training mode and then try it out against a grappler in a live match to avoid their basic tick throws, just as Mai does against Yashiro in the above video. If the opponent whiffs a command grab, there's enough time to react and punish with a combo once comfortable with this technique.
Breaking Alternate Guard
Alternate guard may initially come off as being overly powerful against tick throws, especially in conjunction with KOF's long throw invulnerability length. But just like with any good strategy, it can be countered and cleanly beaten.
Lows
Since you are alternating between high and low block, you become quite vulnerable to lows, but this is usually a fair trade, as grapplers, who you would usually alternate guard against, tend to not have very damaging options from lows.
An alternate guarding player will be vulnerable to low attacks about half the time, though due to the leniency for staying in blockstun players can slightly delay the time spent crouching or standing, so they may stay standing more than crouching when alternate guarding. Regardless, there's always a chance that a low attack will hit.
Characters that can chain Crouching Light Kicks such as and confirm into a knockdown (Benimaru and Vice come to mind) have an easy answer to alternate guard. Others like Clark can still combo from a low light kick, though since his hitconfirm incorporates less low hits he's less likely to hit the opponent on his first try. Delaying the timing of a low chain can further the chances of success, though a well-timed sweep is enough to get the job done.
Even Daimon, who can't chain any low hits, only needs to land one hit to break the opponent's guard: once hit, the opponent will have to block an attack to re-enter blockstun so the pressure of being thrown reappears despite not getting a knockdown or combo.
Overheads
Though overhead attacks are usually slower than lows, they're just as capable of breaking through an alternate guarding player.
Most grounded overheads are safe on block and certain ones could be comboed off of like Raiden's Close Heavy Kick which could be canceled into an HD combo. Daimon's 
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is difficult to react to, causes a knockdown, and it can be canceled from Standing Light Kick for a fast low-high mixup.
A more universal option is to simply hop in on an alternate guarding player. The chances are that the defending player will initially be looking out for a whiffed command grab attempt rather than keeping an eye out for when to anti-air and so even if the opponent successfully blocks the jumping attack the attacking player is at point black with enough frame advantage to continue to break through the alt guard.
Guard Break
The longer a player stays alt guarding, the greater the chance of the opponent breaking through with one of the above methods. Even if able to correctly defend against the grappler's attempts at breaking their guard, eventually this would push toward a true guard break which would allow the grappler to land a full combo for free. An alternate guarding player will eventually have to find a way out if the grappler isn't whiffing a grab. Each way out carries a risk of its own just like anything, so there's not a free answer since either Guard Cancel option isn't fully safe, attacks could lose to frametraps, grapplers can quickly run back in to stay close, reversals could be baited, and backdashes, rolls, etc. each have a counter.
Pre-empting
Simply grab the opponent before they have the chance to go into blockstun. This can be done in multiple ways:
- Perform an empty hop at the opponent and immediately grab them upon landing.
- Run forward while buffering a command grab and throw once in range.
- Land a hit such as from a cross up or from breaking the opponent's alt guard, then throw afterward if attempt to block in anticipation of an attack.
- Scoop the opponent after a hard knockdown by delaying a command grab attempt. This works when the opponent is expecting a meaty attack and respects the grappler enough to block until their throw invuln expires, and delayed command grabs are even better for this.
These setups can occur quickly from the neutral game and are difficult to predict and react to since alternate guard can't be relied on.