Let's start:
Oden
Momonosuke
Nine Red Scabbards
Shinobu
Yamato
almost EVERY Princess
- Rebecca (Useless)
- Shirahoshi (Cries too much)
- Masherry (KILL IT WITH FIRE)
- Vivi (BORING)
- Pudding (Tsundere/Yandere overused)
EVERY Kid character
Shanks
Mihawk (his only job is to look badass for the Zolo Fanboys)
Dragon (DO SOMETHING)
Big Mom
Orochi (despite this he did nothing wrong)
Tashigi
Ace
Usopp
Chopper
Nami (only good for fanservice)
Robin (boring and only good for fanservice)
Sanji
Zoro
Condom Boy