Mario first meets Parakarry on Mt. Rugged (though Mario can optionally find him standing in the Post Office earlier in the game, before Chapter One to be specific). Parakarry explains to Mario that he has lost three Letters and asks Mario to retrieve them. After Mario recovers the Letters and returns them to Parakarry, the Paratroopa joins Mario's party seemingly out of both thanks and as a wish to assist Mario in finding all of his other lost Letters. Outside of battle, Parakarry can carry Mario for a short amount of time, flying over gaps Mario cannot Jump over. With Parakarry on his team, Mario can also deliver the Letters he finds by talking to their recipients with Parakarry out on the field. Parakarry has a Defense Power of 1.
He also receives two letters at the Post Office in Toad Town: one from Frost T. thanking him for delivering his letter, and one from Whacka who admires his ability of flying.