Well their ATK and DEF are each "?", And they each start off with a Different level from 1-6, Lighty is the lowest with 1, and Earthy is the highest with 6, They have 3 classes according to Yu-Gi-Oh Wiki, with them being:
Monsters gain x200 ATK/DEF for each of their own levels.
Class A monsters: Fortune Lady Lighty, Fortune Lady Firey.
Monsters gain x300 ATK/DEF for each of their own levels.
Class B monsters: Fortune Lady Windy, Fortune Lady Watery.
Monsters gain x400 ATK/DEF for each of their own levels.
Class C monsters: Fortune Lady Darky, Fortune Lady Earthy.
During your Standby Phase, their level's will Increase by 1, Earthy has an effect that deals damage to your opponent every time she level's up.
It's hard for me to explain, but here's the Link to them on the Yu-Gi-Oh Wiki for a much better explanation as to how they work :P.
Fortune Ladies on Yu-Gi-Oh! Wiki.
Nisa and Pram........My Strongest Mage and Fist fighter yet and only getting stronger....FLAT POWER! XD *is frozen by Pram then busted into pieces by Nisa*.
Current Obsession: Disgaea 4.......And Hii-chan X3.