These are general tips for Chatterbox.
Units with AoE Pierce damage such as Laplace, Snow White, and Maxwell are very powerful against this boss as they are able to damage to all of his weakness points as well as his main body at once to deal x4 damage. Rocket launchers are also able to achieve the same effect with their AoE normal attacks. Laplace and Vesti are good RL DPS for this boss.
Shotguns such as Drake are also good options to bring as Chatterbox is in close range for much of the fight and they are able to consistently hit all 10 pellets against the boss’ large hit-box, dealing good damage and generating lots of energy.
As Chatterbox’s Long Range Fist Pound is extremely telegraphed with a long windup time and only affects one target (unless core is broken), shielders such as Centi can be extremely valuable in blocking the damage.
Chatterbox goes through a cycle of jumping to a far distance and then doing a fist pound onto one unit. Then he will shoot missiles from the missile launchers on his back, which can be destroyed though there is a short time to do so, and then will charge up a powerful attack which can be interrupted by hitting the two interruption red circles.
The missile launchers will regenerate when he jumps back to the far distance and will sometimes also launch missiles which can be destroyed as a second salvo.
Destroying the core of Chatterbox will significantly increase the damage of his far jump fist pound, which will deal significant damage to three units. Avoid destroying the core for an easier run.