All of Bonney's major weaknesses (she isn't that broken)
As someone who is going to pull for Bonney tomorrow, I spent some time looking over her traits. While she seems overwhelmingly strong, being able to change and perform all 3 class roles, it’s not as broken as you might think. She is like 80% Attacker, 10% Defender, 10% Runner. It’s no worse than EH Chopper being able to switch roles.
Her main gameplay loop is building and activating Solo Boost. In that alone, it comes with some weaknesses… She cannot control her Solo Boost or choose when to use it and her 1-HP trait is only active during Solo Boost; she can be one-shot any time it isn’t active.
As an Attacker, she only Ignores Revives against Celestial Dragons so other EXs (like D. Roger, Kizaru, & H. Kaido) aren’t affected. She also only removes ATK Increases from Blue and Dark elements while in Attacker role. At least her +30% Damage Reduction is unconditional so this is the best class to play while moving around the map. Unfortunately, anytime you want to switch back to Attacker, it requires spending one of your skills.
Defender is decent but it’s pretty much only useful if you have no other Defenders on the team. As we saw in the gameplay, she fills her Solo Boost gauge faster from attacking instead of filling the treasure meter. In order to switch to Defender, you have to start your counter which means sitting still and doing nothing while you wait for it to end. Any Runner with ignore-capture can just come in and take the flag back from you while you’re stuck in the animation. Bonney also only gets her extra +30% Damage Reduction while in the Treasure Area so the moment she leaves it as a Defender, she is significantly more fragile. Also since her Solo Boost can't be controlled, if it fills and activates while you are busy filling the treasure meter alone, then it is pretty much wasted.
Runner is by far her worst element. I’d almost rather not have it at all and just give her other traits. It could be useful to clutch, but it’s very weak overall. First, Bonney has no mobility skills so you shouldn’t even be focusing on capturing treasure as her. Secondly, she doesn’t have ignore-capture. And then most importantly, she only gets +50% Capture Speed and +30 Damage Reduction if there are no allies in the treasure area which means her teammates are actually detrimental. If you see a teammate Bonney capturing, LEAVE HER ALONE. Capturing treasure (especially a completely filled one) fills the Solo Boost gauge pretty well but again, if it activates and no enemies are around, then it’s a wasted opportunity. And similar to Defender, the moment she steps out of the treasure area as a Runner, she loses her DR and becomes significantly more fragile.
Obviously only time will tell, but she definitely has limitations already in place on her abilities. My guess overall is that she will be tanky and hard to KO. She will have good match-ups against a lot of characters, but she won't be oppressive in the Defender role, or constantly turning the game in Tons of Treasure like Luffy or D. Roger did.