Okay.
The trick is to not add or delete any memory, and also not to mess up the pattern, since that will lead to a crash.
Now let's say you want to just change Beatrice's fighting style to N_Striker_A. All you have to do is overwrite "GS_Female_A" with "N_Striker_A" since they have the same number of letters. Simple as that.
On the other hand, if you want to change Zoe to a dropout style, that requires more work, since DO_Striker_A has more letters. What you do in this case is copy from "Medium" (or whatever it is) until /Anim/GS_Female_A.act.. (make sure to include the dots). Then, paste over, let's say, Leon's dodgeball model's stats (which is from "Huge" until "/Anim/DO_Striker_A.act..." [can't remember the number of dots]). Now, do the opposite. Copy normal Leon's stats from "Huge" until /Anim/DO_Striker_A.act..." and paste over Zoe's stats from "Medium" until /Anim/GS_Female_A.act.."
I hope that helps. Good luck.