The Avengers and the Fantastic Four were a part of keeping Hulk in check, as well as the Teen Brigade. In The Avengers #2 (November 1963), they called Giant-Man (Hank Pym) to help defeat a Space Phantom. They contacted the Avengers to notify them about the whereabouts of the rampaging Hulk in The Avengers #3 (January 1964).
The Avengers and the Fantastic Four played a role in containing Hulk's actions, along with the Teen Brigade. In The Avengers #2 (November 1963), they summoned Giant-Man (Hank Pym) to assist in defeating a Space Phantom. They alerted the Avengers about the whereabouts of the rampaging Hulk in The Avengers #3 (January 1964).