Well, I can name a few, but I can't remember them all right away. Emerald dragons are good against earth magic (stone spikes, meteor shower, earth shock). Undead are not susceptible to (plague, wasp swarm, confusion, berserk, blindness, banshee's cry, which makes sense since they are undead). Golems (slow, blindness, berserk, confusion, basically anything that affects non-living mechanical creatures). Titans (berserk, confusion, anything that affects the mind). And so on.