Remove state on action

I've searched this but it seems the on the threads I've found, the person trying to do this got instructions but had issues, and then resolved it away from the thread without any info on how they got to that point.

I just picked this up on sale two days ago and am having a lot of fun with it. I've made games before with gamemaker but I don't have any real coding experience.

I would like my boss to have an attack where he charges up for one turn, and then he releases the attack after. I couldn't find a way to guarantee that the boss used the attack after the charge, so I have been trying to find a way for that state to persist until he uses the skill that requires the charge.

I have YEP Battle Core, and all three action sequence packs, but am still learning how to use them.

No need for Plugins, this can be done with the enemy attack pattern alone or with a combination of attack pattern and skill/state depending on what exactly you want.

At what time or Situation should the chargeup start? Random, certain turns or what else?

Edit: Ninja'd by Andar.

Hey thanks for replying so quickly. I just got off work.

I have made the charge up a skill the monster will use. Like in Dragon Quest or Persona when the monster prepares an attack and it tells you.
So when the monster uses it, it will be charged to be used on the next turn (preferably although I don't know how to force it to use a skill pending a condition being met), or it will be used whenever the monster decides to.

The idea is to encourage the player to guard if they don't want to take massive damage, hopefully adding some thought process to the fight instead of just mindless attack/be attacked.

that doesn't really answer my question, because you don't explain when the chargeup will be used.
so you'll have to use the more complex solution...

Make a state that has no effect, no icon, no messages and a duration of exactly two turns. Call it "charginf for xy" or whatever.
Make a skill that applies that state to the user/enemy with the message you want, like "is charching".
on the enemy that should use the skill, make an entry to the action pattern for both this state skill and the chargedup skill. Give the state skill whatever conditions you want.
on the charged up skill, give the condition of "has state charging" and a rate of 10, making sure that the regular skills stay at a rate of lower than 7.
finished.

the powerfull skill will only be usable if the state had been applied, and the duration of 2 will remove the state at the end of the following turn.

EDIT:
and no, this has absolutely nothing to do with javascript or plugins, that is basic enemy behaviour in the database...

Oh wow yeah, this is working out.
Didn't even need these battle plugins. Thank you very much.

As for not answering your question, I meant to when I typed "So when the monster uses it" but I was tired from work so I didn't really articulate it.
I meant to say, "When the monster uses the charge skill"
It is a skill I had created as a charge up for the big attack.

I understand the rating system better now, although it's weird the maximum is 9. Either way, figuring that out has helped immensely.

Thank you very much.

Even that is not an answer to my question, because it still doesn't answer the question on when exactly the enemy decides to use the charge skill.
A correct answer could have been "every five turns the enemy uses the charge skill" or it could have been "the enemy uses the charge skill randomly" or "the charge skill is used when the enemy is below x% HP" or something like that.

The answer above works for any option including a random one, but there are other answers with simpler solutions if the charge skill is not used randomly. For example if you would have the charge skill used every fifth attack, that would have a solution without any state.