Actually, you can make a lot of that with events by using status effects. If you make a status effect cancel out other effects, they can't be added while having those special status effects.
A money-add would be rather easy.
class Game_Enemy
alias gold_addon_later gold
def gold
return RATE * gold_addon_later
end
end
Same for EXP from enemies:
class Game_Enemy
alias exp_addon_later exp
def exp
return RATE * exp_addon_later
end
end
Counter attack was a planned add-on, I was going to use a status effect for it. Something like "when STATUS_ID then return COUNTER_PROBABILITY", I just didn't have time yet.
The weapon status would be easy as well.
class Game_Actor
alias element_set_addon_later element_set
def element_set
return element_set_addon_later if @states.include?(STATUS_ID)
return []
end
end
The armor status protection would be a little more complicated as well as the armor element protection. I have implemented element absorbtions into CP (comes in the later part of the game) and I found out that it's a rather confusing system that isn't so compatible with other stuff.
Those mini-systems themselves are not so complicated, but the whole Mana stone system of FF9 would be quite a messy script with many compatibiliy issues.
Oh, if you want a Materia system, Seph made one long time ago.
I think I'll make my own Steal for Tons as I know that Trickster's Steal is merged with his Scan. I should be easy using the Multi Drop code as reference.
@Sin86: I forgot to set those add-ons to false. !false is the same as true, just quicker to type. xD Simply remove the exclamation marks to turn those add-ons off.