Additional effects for attacks

 I have attacks that are supposed to do add buffs/debuffs to characters other than the target.

 One character's attacks buff a different character (a beast master and his pet. their attacks are supposed to buff one another while attacking the enemy).

 The other is a warrior that sacrifices parameters for bonuses (for example, trading Hit % for bonus damage or increasing evasion for a loss in damage). These are supposed to be done while attacking.

 I can set the bonuses to states.... but I'm not sure how to have the action add a state to the attacking character (as opposed to the target)

Use the damage formula, a referring to the user.

a.add_state(#); a.atk-b.def      or whatever your damage part is.

it will apply before the damage calculation.

can probably do the same for party members instead of a, but I don't know the exact method.

cool :p

still need to figure out how to make it so that one party member can buff a different one.

At the very least you need to determine if both the beast master and the pet are in the active party, unless their presence is automatic.  Then using that, you could do a forced action.    All of that could be in a common event which the skill calls up.

 How would I go about seeing if both of them are in the active party?

 I was planning on giving each one of them a neutral state somehow and then have the abilities check for having a character with that state in the party. Unfortunately, I'm not certain how to add a state to a character in such a way that they innately have it.

 I suppose I could have their attacks add a special condition to whatever they attack and have it so that, if a character attacks something with that condition, the forced action could run?

 I'm not 100% sure on how to pull this off though.

First you need to find out who is in the active party.

Control Variable [0030:Active Party #1] = Member #1's Actor ID

Control Variable [0031:Active Party #2] = Member #2's Actor ID

and so on for as many as are in the active party.

Now, assuming your beast master is the one using the skill, you don't need to worry about that character; you only need to find the pet

Use Conditional branches nesting inside one another which draw on the data in those variables.

If the actor ID is the pet's, then forced action.

Else: move on to the next party member

For your final conditional, if it finds that the pet isn't any one of them, you could put an appropriate bit of text e.g. "It would help if X was in the party!"

This can be much simpler...

The Beast Master attacks can run a common event:

Conditional Branch: Pet is in party:

 Actor Change State: Pet to x State

Simple as that... This would only work on the assumption that the Beast Master only has one pet that does not change during the course of the game.

If the Pet has skills that buff the Master then do the same but the common event tied to the skills would check if Master is in Party and change state of Master.

I could be misunderstanding entirely xD but that is how I would do it.

~ Dinhbat

But doesn't that just determine if the pet is in the party? i.e. it does not determine if the pet is in the active party, it could be in the reserve party.  Of course, if the number of characters = the same number of active party members, then there wouldn't be a problem.  But that is often not the case.

Correct but since it is not forcing action and the pet is not in party there is no harm in adding a state to the pet if it is in reserve