Here is the story, extended a little bit compared to what I wrote before.

Be creative!  I do not mean to script this too much.  I leave the fight choreography to  you ...  Perhaps it is easier to do the fights standing  up, than on the ground, so perhaps more standing up would be good. It  would be great to see several of them attacking her at once (perhaps  show them whispering strategy to each other).  I would love to see  more belly punching ... if you do,  it really would be nice if one  could actually see her belly and her belly being punched!!  I realize, this is all acting, and you certainly do  not want to harm Casey in doing this movie ... but too often, those belly punches or other types of punches are "hidden" by some other actor between the  camera and Casey. Hopefully, there is a way to show this more  clearly!   Also arm bars of sorts. Indeed, if you take the fight to the ground, it would make sense for some of the guys to try to get her into holds or armbars or to punch her belly.

Actors: 

1) Casey, in that black leotard with a red belt, knot to the side (as in the previous one).  It might be good to start her off wearing a karate jacket over that, which she takes off before that first fight just like in part 4.  It is ok for her to wear tights, if that helps the actress ... could you pick some shiny ones then, though?

2-5) the actors from the previous movies "Casey vs the team of Karate"

6, 7): two more actors.  They will be the one that lent the other four their black belts in the previous movies.

In "Black Canary Casey", you had one or two big guys that gave her some real trouble ... not too much in the end, but it made it interesting.  Perhaps ADDING two big guys to the previous four "team of karate" could be an intriguing way to go.  If not, that's ok.

It would be best to make these quite a number of short fights (each perhaps two to three minutes or so) rather than, say, four long fights.  Also, if she wins one of those fights, perhaps the guys aren't completely knocked out ... they may just be on the floor whincing, crawling around, making it clear that she won ... after all, they have to get back up and fight AGAIN!

I think the best way for this story to evolve is for the six of them to wear her down.  After all, she is fighting six men now! So, is starting to get tired, and it becomes increasingly difficult for her to defeat those six, and they start to notice.

As for the story:  [ ... I think in Casey vs team of karate part 4,  TWO of the fighters had borrowed a black belt, the other two just white belts ... so ... ]

 Casey trains again: in karate jacket, underneath that black body. Red belt, knot to the side.  One sees six black belts and two white belts hanging over the ring.

 Six men walk in: the original four plus two new ones.  They all wear white belts.

Casey turns to the new ones: "who are you?"

The new ones: "We lent our black belts to our friends here, and you took it from them.  We want them back!"

Casey: "Ah, some new friends!  Shouldn't there be two more?  I got four belts from you last time!"

One of the old ones: "We bought those white belts.  Any beginner can get them.  The black belts are valuable."

Casey: "So your two new friends here [ she points at them ] have even lesser black belts than you?  That should be fun!"

The new ones: "Give them back to us, or we will beat you up!"

Casey: "alright, I had enough of this.  I don't know what to do with these belts anyhow.  Here you go."

[ She hands the belts back to them.  They tie the belts around their wastes].

One of the new ones to the old ones: see, she got scared!  This was easy!  She would be no match for us, so that's why she gave them back to us!

Casey [ listening in ]: oh, you think I am scared of you?  

One of the new ones: yeah, you deserve to be beaten up, after what you did to our friends here! You think, handing us back those belts will save you, little girls?  

Casey: "Beat me up? [ She is amused and laughs, then gets serious: ] 

 Dare to come in my ring and I beat you up.  I challenge all six of you to take me on!"

The guys are grinning, getting in the ring.

One of the old ones: "You want to take on all six of us?  You are crazy!"

Casey: "I like a little challenge!  Besides, I can easily defeat even the six of you! But if you win,  you get your belts back!"

Now, sequences of fights ensue.  She keeps on giving them various handicaps.  She might say, for example:

"Six guys against one girl!  That's not really fair!  I mean, this was too easy for me, I want a bit of a challenge!" and then offers another handicap.

But then she becomes too cocky.  She claims, that she can fight them all, having  her hands tied behind her back and being blindfolded, with three of the guys holding her and three attacking her.  She does resist for a while, but eventually,  they manage to knock her out, and tie her up with the white belts.

She comes back to her senses. The six guys wear their black belts.

One of the new guys: "Why were you  so afraid?  She is just a weak little girl!"

One of the old guys, showing off to her: "We are the true champions and black belts!   You will  not take them away from us again! And good luck untie-ing yourself!"  They all laugh.

Casey: "[ Defiant ] You haven't won.  I can still beat you up, even while being tied up!"

So, another sequence of fights ensues.  She manages to untie her herself, and eventually beats up all the guys.

She takes off the black belts from the guys again.  

Casey: "What do I do with them?  I really don't need them. Ah, I have an idea!"

She ties up all the guys.

Casey: "I should call the police.  Six guys attacking a helpless little girl, who was all alone training in the gym.  How rude!  You will be in jail!"

She laughs at that joke. 

Casey: " Thanks for the workout, guys! Good luck getting out of your own belts!  Let me know, if you want to try  to beat me up again sometimes!  I always enjoy a nice little brawl against pathetic fighters like you! "

Walks off, the end.