There are three different kinds of dances. All three kinds fail often, so never count on their doing good damage all the time. Pair up three of them with another character (such as Light Armor) for maximum potential. Here's a lowdown of the pros and cons of the different dances.

Devil Dance: This is if you pair them with a normal dragon. The good thing about this is that it's far less risky than the other dances; the only spell that doesn't do good stuff is Heal Enemy HP, which only executes randomly during melee battles, and Heal All, which rarely happens on the field (but only at level 10). However, the attack spells aren't nearly as strong as the other two. What's more, the spells do have elementals, so if you're in the wrong place (e.g. on a bridge or in a forest) when the wrong elemental goes off, you're in deep brown stuff.

Reggae Dance: This is if you pair them up with an Unknown Form/Behemoth. The list of dances here is better in melee battles (not to mention the Behemoth can only attack in melee battles anyway). In the field, you've got three out of eight spells that will have bad effects (like healing the enemy or hurting you). Inside, there's only one. And if you've got three Mini-Devils with Reggae Dance level 10, you can do some real damage in battle... if you're lucky. However, even outside of battle this can wreak some major havoc since three out of eight spells give incredibly powerful damage at level 10. Probably the best one to team them up with if you like using them.

Fright Dance: This is if you pair them up with a Uni Uni/Black Dragon. By far the riskiest and strangest dance. The main addition here is two field spells called Complete Heal All and Frog All. The first completely heals all HP and MP for every unit on the battlefield; the second does 25% damage to every unit. Complete Heal All can be really useful sometimes; it's the only spell that restores dragon MP! And if there are a lot of undead enemies (such as in the Persona or Temple of Memory fight) you can even damage them with it! The good news is that if you've already beaten a bunch of enemies, you'll be completely restored while they'll stay dead. 8-) The bad news is that if you're up against some strong enemies and this is used, it'll erase all your hard work. Also, the rest of their field spells are a real toss-up; only four of them will do real work for you; the other five will work against you in some way. In melee battle it's a bit better, but not by much. Use if you like risks!

When using Dances, it's probably a better idea to be close to enemies but not friends. If you heal enemies you generally won't heal for that much HP, but if you damage your friends you can really put yourself in a bad position. And their good attacks (Bagdem, Super Secret Attack, Ragnarok etc.), when they happen, can easily do 9999 damage. 8-) If you want to cheat, do this: save your state, try a dance; if it's not the one you want, restore, have another unit do its turn, save again, and try again. Repeat as necessary. This only works for field dances, though, not melee ones. (Field dances are decided after each unit takes a turn, so it won't change, but melee dances are really random.)