I just felt like taking a big risk and suggesting something completely different. Here goes;
Chlorophyll. It doesn't play the getting hit = effect game, but assuming weak armour's speed boost makes it a worthwhile ability, Chlorophyll's speed boost will surely be helpful. Against the trade-off of every fire-attack bringing 4x the pain; giving it a mean risk. But because it requires a turn of set-up (or giving away your ability by having a ninetails in team preview) the effects aren't as instant as illusion/weak armour. Sun itself is pretty risky, but CAP4 doesn't even have to work that well in sun; just an alternative to agility/rock polish (or better; should those 2 not make the moveset) that also kills a turn of rain teams is potentially a pretty defensive reward.
Alternatively if you don't use sun, Chlorophyll won't do anything, giving you that NCA option you've been looking for, if you want to threaten things with CAP4's stabs at any time in the game, but without risking a defence drop.