The one thing I like about Chopper, is that he always rises to the occassion, even if he acts cowardly at first.
He has demonstrated time and again that when back's against the wall, he picks up the phone answers the call
Chopper's Finest Hour:
Against Big Mom, a character stronger than 99.9999% of the OP world and her fleet, Chopper was willing to sacrifice himself to protect his crew. Chopper had this to say before facing his death:
What a beast
Even Perospero, man who has sailed the New World with a Yonko crew for decades, was shitting himself at the sight of Chopper: