Voltorb are dangerous.

Built by a rough enterprise designing weapons for terrorist organisations. They wanted to make the new missile, a bomb that could sneak in undetected untill it was too late.... andthey suceeded. But unknown to them was the fact that it began to learn, taking in it surroundings and acting like a living creature.

It was when they relesed them for a terrorist attack that it all went wrong, they overid their original commands and fled.
They learnt from things around themselves mostly pokemon and learnt to live along side them. As they watched they realised about evolution... so they evolved. Making themselves stronger, defencivly better and overall a better weapon. Id imagine soon their evolution will learn to evolve once again....

They 'feed' on electrical currents and move by rolling, as they have a gyrator mechanism within themselves.
When exploding they open up so the rest of the shell doesnt get destroyed.

Hope you like it