Immaterial and Missing Power/Autoguard
IaMP has a couple of autoguard mechanics in place, partly inspired by the nature of the game where high/low mixups and sequences can alternate back and forth with great speed. Without the default autoguard mechanism it would not be possible to block everything that can be done by the majority of characters. The stagger system is also an extension of the autoguard and spirit system as a means of capitalizing upon the lack of autoguard.
Every attack in IaMP has 3 levels that correspond to the standard attack heights in pretty much every 2D fighter ever created: high, mid, and low, with mid attacks being blockable using either 1 or 4 while high and low must be blocked correctly. However, unlike normal fighters where an improperly blocked attack will hit you, IaMP has an autoguard system in place which both helps the players' defense while adding a metagame element of spirit drain which allows the attacker to capitalize off improperly blocked moves. An improperly blocked attack will still be blocked but have a red flash effect instead of the normal blue one; in addition, there is a spirit penalty depending on the move in question. An attacker with quick high/low can very easily drain an entire spirit bar if the opponent guesses wrong two or three times, leading to a guard crush. At that point, autoguard will not function until the spirit bar is regenerated, and the opponent will be subject to staggers.
After an air recovery, the opponent will be in a state of autoguard so as to prevent potential crossup silliness and also to facilitate midair reversals. If you do not attempt to do anything after an airtech, you will autoguard the next incoming attack. Of course, this leads to being possibly guard crushed in the air, so it's not always a good thing. The autoguard duration lasts for one attack string or until you attempt an action.
Pressing start and switching on autoguard in the handicap box will give an entirely different autoguard to your character. This will be actual autoguard where all incoming attacks are blocked regardless of what you do; however, height requirements still apply and you must be holding some form of crouch (1, 2, or 3) to autoguard low attacks and some form of standing (4, 5, or 6) to autoguard high attacks. Guard crushes will still work as normal, though.