The other trick typically is to use attacks on creatures that "won't destroy them only damage them like I primarily used "demi" because it technically damages the enemies but it doesn't "destroy them" and 90% of the time it won't be absorbed and the enemy will usually counter, now for more obscure and unlikely skills use the command materia "manipulate" on tons of creatures such as adamantoise to get "big guard" which it only uses on it's self otherwise and it works on some weak enemies like the moles I mentioned that have l4 suicide you can get it either or and if you have the manipulation crown equipped then manipulation will work more times than not though some creatures can not be manipulated even amongst normal creatures but, try it where ever possible and keep in mind too that some boss looking creatures have skills that can be gotten only once or otherwise hard to get for example "triad" can be gotten by the mechanical spider in a mountain but, if you defeat it without trying to get it to use it on you, you might never get it.