Ah, sorry, I worded that wrong. I mean, how should a good player be able to punish these things? In Melty, you have EX-shielding for projectiles and throwing for turtling, but can anyone think of different ways to counter each? I've been toying with the idea of "catching" projectiles instead of simply blocking them, and shoving or tripping someone who's turtling-- and if they're air blocking, you could shove them to the ground and they'll take damage or be stunned. I'm also thinking about having a guard meter that only reduces with certain obvious, slow, high prorate, or other severely penalized moves. You wouldn't be able to combo off of these moves, so you would never throw it out randomly unless you knew they would block it. But actually, turtling can be fixed by my "special thing" too.
Throws are a must for any fighter period. Parry systems are also starting to become somewhat standard (even Guilty added Slashback).
IMO Guard Meter should reward aggressiveness and penalize defensiveness. If you're on offense, risking your neck, then the few times you do block, you should take less damage. If you're on defense all the time, then the more you block, the more damage you should take, until you get guardbroken and eat a combo.
As for anti-air blocking, I really like Guilty's mechanic for that, how you can't air-block a ground-based move unless you Faultless Defense. That's not to say you need a Faultless Defense system, but perhaps the only way to "block" a standing move from the air would be parry?
Just throwing my 2 cents in here.