You are the eater of the Chimera chimera fruit, giving you the power to morph parts of your body into any form of animal parts, want pray mantis arms, got it, want the tail of an ankylosuarus and the legs of a cheetah, Snake for an arm covered with Pangolin armor and a marlin nose sword, you got it. You get the gist.
You meet the straw hat pirates when they reunite after the two years apart.