At some point in his life, Whitebeard ate the Gura Gura no Mi. The destructive power that this fruit granted him contributed to his being known as the strongest man in the world.

How many Devil fruits does Whitebeard have?

The climax of Blackbeard's character build-up was during the marineford arc when he surprisingly wielded Whitebeard's devil fruit powers. This was a surprise for everyone because he is the only person known to ever wield two devil fruits. So, let me discuss briefly how this is possible.

What is the most powerful devil fruit?

1 Gura Gura no Mi: The Strongest Paramecia Ability

Using its powers, Whitebeard could bring the ocean currents to Tsunamis-level and destroy with enemies with quakes. The Gura Gura no Mi is so powerful that it is widely known to hold the power to destroy the entire world.