Attack combos are a fundamental part of action games and stagger/stunlock mechanics let the player actually use those long flashy combos. But how do I balance it?
I like the dark souls approach. Keep attacking to decrease poise and you get to do a full combo when the enemy is stunlocked. But I'm not sure if it's good for fast paced games. And it's not visible to the player.
KH lets you stunlock enemies until you land enough hits and then let's the enemy get revenge. This mechanic is called revenge value. But I have not played the mainline entries that actually have that mechanic so I can't comment on whether or not it works. It also needs a well telegraphed counter attack animation to be fair to the player.
Some games don't bother and simply force the combo to end with a knockdown attack to let the enemy recover. This is extremely common in beat'emups. You can easily stunlock a single mook but then the other enemies will flank you as you do so. I do not know how they handle heavier enemies that can't be stunned as easily.
I haven't played DMC/Bayonetta so I don't know how they work either. But they probably have a good system.
Implementation in code is not the main problem for me. I just want to know what type of system is a good fit for a relatively fast paced action game.