White Lightning Productions

the NOT KRIS sign.

According to the Wiki and the story line, Butch is pretty well buffed out and being young, she's fast. Any systems she learns would be complicated by the fact that they are designed for Smoothskin humans, not Were's. Werewolves are digitigrade and have faster reflexes than Smooths, and I suspect that would affect Rebecca's fighting style.
There's also the sad fact that not a single Wolf would willingly work out with her in Werewolf form, to smooth out the differences encountered trying to use human fighting styles as a Werewolf.
While her relationship with her father is strained, outright hostility is forbidden by both Jack, the Alpha; and Sheriff Con, the retired Alpha.
I do suspect that there will be some surprises for us there, courtesy of Kris-but it won't be for a while, yet.

My guess is that Butch is cunning enough to quickly adapt. So if she doesn't be defeated in the ten first minute of the fight (it's highly probable that this happen) she could find a way to use what she learned. Also, I think that Uncle Con could accept to be her sparring partner if she beg well enough and honestly promise to not abuse of her training. He's a nice guy that could understand the need to Butch to challenge Gus. The problem is that I doubt that Mister Nero could trust Rebecca to not use this training to win Peter or reply to Jean taunting.

Elle n'a pas assez de sang-froid.

S.P.P.

Quite right. I suspect that the substitution for heel-based strikes (when you don't have normal heels) would be either some sort of jab, (foot extended, toes stiff) or a sort of side-of-foot blow. If we include the claws, then a raking attack/defense is also possible; although the risk of inadvertently "making a thrall" that way con't be ignored.
Gotta wonder: might such a thrall have a "foot fetish"?

I'd say Butch has a Base Attack Bonus of +8, and does 1d10+5 points of damage.

Yeah, but after two rounds the Bonus drops to +3 (excitement) and her damage drops to 1d10+2 (lack of consistent method). Basically, she gains a +2 from advantage: Surprise. That goes away fast, once she's identified as a: alone, and b: either superficially trained OR her Wulfen nature takes over. Wolves are not sophisticated fighters alone.
I'd further suggest a base AC of 6, due to strength and healing capability, as well as speed.
She's a get in and get out sort of fighter. While she is strong, I wonder at her endurance.
She might have some sort of boost from appearance; she is pretty, both as a Human and as a Werewolf. I'm unsure as to any benefits she might gain unclothed...in a fight, there are more important things than cheesecake.