Buff medals are where you want to place Defense Boosts and Attack Prize Plus's. If it's a buff medal that also has a nice attack you might be able to justify the skill Attack Boost II and Attack Prize Plus. You could also place Second Chance on one, as many people have done with their Illustrated Kairi's. (For those who have one. Not me. T.T)
If you get a Sebastian, Sebastian with his 6 cost needs a skill like SP Cost 1 or 2, or No Cost. I believe that the first two always trigger but not No Cost, so I'd be careful.
Strong attack medals you want Attack Boost II, Attack Boost II Max, Attack Boost II and Attack Prize Plus, or Attack Boost III. Attack Boost II and Lux Plus is nice, too, I suppose.
I'm still yet to find the best use for Poison, Paralyze, Sleep. They're very situational whereas the above skills will save your butt many times.
