I think its just a shading/drawing effect!If chopper had Coa,Oda would state so in grand fashion!As for Peros arrows,monster point chopper just has a tough hide!Chopper making Queen Bleed was just the YC2 fucking around with chopper!If Oda actually give an opponent that can be beaten by chopper and has Coa,he could unlock it maybe!
Chopper's future PU will be awakening and formulating a rumble ball formula that gives him crazy powerfull transformations!EOS chopper should be a brute strength juggernaut!If i'm not wrong,Jack who is YC3 1Billion berry bounty monster doesn't have any haki,said by Oda in a sbs!