Thanks for the guide. For anyone wondering, you can use the following:
C or More - Tamaki, Yuma, Sasara, Harumi, Yocchi and Ilfa,
B or Less - Konomi, Ikuno, Ruri, Charu, Ma-ryan, Nanako, Sango and Luuko.

For anyone not mentioned (like Monaka) I'm not sure if they count which seems odd. In the Japanese version however the two skills are called '85 and above', and 'under 80' meaning a 5cm band where characters don't count as either. So it is likely they fall into that group.

Ah no worries, I managed to figure it out through trial and error.
It’s kinda hard to tell which characters have a larger bust because of the way certain class armor covers them up

Anyways, I appreciate your guide
Thank you 😊

Sorry, been a while since I bothered playing this game (mostly due to it's random unbalanced game play and newer games), and as I've just seen the original guide posting is gone and trying to find info is, well, I don't know how I found the original walkthrough/party planning before (but google isn't bringing up a useful search).

What characters did you use for the C or more one?

I tried using Ilfa Tamaki Haruka, Sasara, Yuma but it didn’t work?

Ah thanks, I’ll will be trying that out!

Use the listed characters.

How do you unlock those party effects?