I am attempting to build the strawhats for theory crafting. Keep in mind that I am willing to forgo effectiveness for flavor but lets get it as close as we can.
This is a link to my Luffy.
https://paizo.com/threads/rzs431zl?Monkey-D-Luffy-build-help-to-polish
To start we a choosing halfling. This for Dex and Cha bonus, halfling luck, slingstaff racial trait, and slipslinger style feat.
Heirloom weapon racial trait for the halfling sling staff.
3 levels of grenadier alchemist. This gets us bombs, ability
Alchemical Weapon (Su), and fast alchemy.
(Considering dimentional excavator archetype for pit traps)
Level 3 feat: slipslinger grenadier. Like god ussop put those alchemical items in your slingstaff.
From then on he is a underground chemist unchained rogue. Potentially charlatan and trapsmith archetypes.
Underground chemist pairs with this because of precise splash at 3rd and this ability:
Chemical Weapons (Ex)
At 2nd level, an underground chemist is able to retrieve an alchemical item as if drawing a weapon. She adds her Intelligence modifier to damage dealt with splash weapons, including any splash damage. She adds 1/2 her level to Craft (alchemy) checks.
You would also grab bomber rogue talent.
Charlatan provides the bluff/liar mechanics.
Feats: Sap adept, expert sniper, pointblank shot, prone slinger.
It would be less thematic but 1 level of veiled blade swashbuckler and weapon versatility would improve melee with the sling staff.
I am struggling with level placements and shortcuts I may have missed. I think this will end up a very decent build.