Infendo.com has a good write up showing a healthy portion of the background stories for the Tatsunoko characters in Tatsunoko vs. Capcom.A mysterious stone known as Skull Stone is split into pieces and scattered across the planet. The stone is said to have the power to reveal the location of the largest deposit of gold in the world.
This legend has entranced the trio of comedic villains the “Doronbo Gang” to persue the stones for the fame, power, and wealth it is said to bring.
However, their hunt for the Skull Stone is not as easy as they imagined, mainly due to the faulty information they receive from their leader, and from the persuit of a righteous duo “Yatterman”.