⇊ Units used, details & music (Please read before asking anything!) ⇊
Note: Remember that they can be different units, as long as they serve the same purpose.
Units used in method 1:
4★ Valentines Titania (Slot 7):
Weapon: Fire
B: Pass 2
A 2-ranged unit with Wings of Mercy 1 (Slot 2)
Units used in method 2:
5★ Naesala (Slot 7):
Weapon: Hatchling
A: Defense +2
Sacred Seal: Distant Defense 3
He has to have 26 Def and 32 Res (visible), it doesn't matter where you get them.
A dancer/singer with Wings of Mercy 1 (Slot 8).
Units used in both methods:
A unit with Fortify Res 2 (Slot 6)
4★ Garon (Slot 5):
Weapon: Fire Breath
B: Escape Route 1
The other units are the ones that you want to farm HM, they must be level 40 (to get max HM) and have nothing equipped (and I mean nothing, unless needed).
Sorry for taking so long, the app I use was being dumb and I spent way too much time trying to make the second solution work, it's not great, but I hope it helps someone without Pass.
If you have any questions, feel free to ask, I'll do what I can to help.
You can check on this later if you're having trouble, as I'm constantly updating it.
Music used:
Persona 2: Innocent Sin OST - Best Girl Theme (Yukino Theme)