MAX mode is like a combination of aspects from KOF98's, KOF2002's, and KOFXIII's ABC/BC button activation modes. Unlike KOF2002 or KOFXIII, MAX mode doesn't allow canceling specials into other specials nor does it allow having previously un-cancel-able normals. (eg. KOFXIII and KOF2002 Kyo's Far D can't cancel into anything, but when in MAX/HD mode, it can cancel into special moves like his rekkas.) What MAX mode now does do is it allows the character to have access to EX moves. Using an EX move during MAX mode takes away a chunk from the draining activation meter similar to how HD cancels in HD mode took away portions of the draining meter. EX moves are only available in MAX mode. That said, EX moves are revamped when compared to KOFXIII. Instead of super fast, just-do-it moves, they're toned in a way that it compliments how it's used within MAX mode. Andy's EX projectile in KOFXIII used to be a super fast projectile that is hard to react to and pops the opponent high into the air on hit. In XIV, it's a slower version of his normal projectile and acts as a fat "Sonic Boom." There isn't any move thus far that is like KOFXIII Kim's EX Hangetsuzan or as I have observed during the whole weekend.
Activating MAX mode also freezes the screen like Under Night In-birth's Chain Shift when activated manually without canceling into it, allowing the player to react to the situation and respond accordingly. But if an opponent tries to hit the activation and the attack overlaps the player's character during the freeze, the player will be hit. So although it recovers quickly after screen freeze, it's not an instant recovery and could be hit right after activation if the attack goes active immediately. An attack initiated after the freeze would generally be blocked though. More testing is required.
When canceling your normal attacks into MAX mode like in KOFXIII, the player's character automatically dashes towards the opponent's character. This is easier than having to manually run up to the other player's character in games such as KOF2002 and KOF2002UM. When doing the MAX mode activation cancel, the screen won't freeze like how manually activating MAX mode does during the neutral game. I can picture larger combos starting from a hit confirm into BC activate/MAX mode activation cancel into another BnB into an EX move that could be canceled into a Desperation Move. We weren't able to really test out if there are ways to cancel Desperation Moves into Climax attacks yet. When using this activation cancel, it consumes 1 stock of meter, which is different than KOF2002 in which it usually consumes 2 stocks. Don't be alarmed; MAX mode's drainage meter is about half the size it would have been if it had been manually activated. Usually players are only able to do two EX moves before the meter runs out, which is limited compared to manually activating MAX mode and having access to about three to four uses of EX moves. Much more needs to be explored with the MAX mode combo system.
