It depends how perfect shielding works - it may already exist.
Firstly, a while ago I think either spunit or Phantom Wings released a code to do with powershielding that did something interesting - I recall they were called 'always PS' and/or 'never PS' or similar. This was during the time that we were looking for a code to change the powershield window for Brawl+ and was a byproduct.
Secondly, spunit also released a set of codes to modify shield variables... You could modify size, decay rate from both attacks and over time, regen rate... I believe Brawl shares the system Melee had whereby you can only Powershield if your shield bubble is appropriately placed, but it might be worth a try using these. You could attempt setting Shield 'max' to something very low (so minuscule that effectively every attack would shieldpoke) whilst completely removing shield damage or degeneration to prevent stupid shieldbreaks. Or, you could keep the Shield max unaffected, but ramp up the damage/decay of normal shields such that attempting to actually hold one or block the attack with one would cause you to pop more or less instantly.
Finding said codes is left as an exercise to the reader... Unless I get bored.
Edit: 30 seconds later:
Code:
Shield Max [spunit262]
04B88440 XXXXXXXX
Default 42480000 (50)
Shield Reset [spunit262]
04B88458 XXXXXXXX
Default 41f00000 (30)
Shield Loss [spunit262]
04B88450 XXXXXXXX
Default 3E8F5C29 (0.28)
Shield Gain [spunit262]
04B88454 XXXXXXXX
Default 3D8F5C29 (0.07)
Shield damage ratio [spunit262]
04B8847C XXXXXXXX
Default 3E99999A (0.3)
attack_damag*(1-X)=shield_damage
Shield Size [spunit262]
80B88478 XXXXXXXX
Is the second set of things I was talking about. You'll have a tricky time finding the first without some very adept searches on smashboards, I think, but they're certainly around (and probably not what you're looking for).
