This sucks. You can do anything if you believe. No training necessary. Peter Pan shit.
Hell, Peter Pan gave them more instructions and a little song to go with it. Luffy said, "Beats me, just pull it out of your ass!"
If Bonney really is this OP, then the only solution is to kill her off. That would be convenient since her fruit can't respawn since it's not a fruit. But it pretty unlikely that Oda planned something like that bc I'm not sure he plans anything these days...