japanese translation help

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I'm reading Shukujotachi No Hankouki by Clone Ningen and I have a really hard time with one page/sentence:
同じ身体をたしなめている奴らに その使い方はかなわない...

To add context to the page:
-The 2 boys are: the main character (mc) who is the head of the student council and his friend Kobayashi.
-The 2 women are: Chiharu, the headmaster and Kiritani, the school doctor.

The mc hypnotized Chiharu to make her believe she's 17 and a sex-obsess teenager so he could fuck her with his friend in the student council room. (hypnotizing is a big part of the story)
Then, while they were washing the place, Chiharu met Kiritani in the hallway. Kiritani who is a lesbian and in love with Chiharu fell for Chiharu's cute and girly side and decided to fuck her in the student council room, unaware that Chiaharu was still hypnotized.
The 2 boys are hidden in the lockers.

So, I don't know how to understand this sentence.
I don't know if たしなめている is the potential form of たしなむ or the ている form of
たしなめる.
I don't know if かなわない here means is not suited or do not rival.
I'm also not sure if 奴ら are the women or the members of the student council. The mc says on the next page that the student council will kill him and his friend.


Oh, and here the link to the manga:
https://e-hentai.org/g/717088/e96dff6381/