I will try to explain with 2 wugu + 1 fletcher vs boss.
Harumi wugu Needle Blow on boss: needle blow starts dealing damage.
Wugu2 needle blow 1s after harumi needle blow on boss => harumi needle blow is deleted. New wugu2 needle blow starts dealing damage. Harumi wugu Needle damage = 0.
Wugu2 wugong gu on boss: wugong gu starts dealing damage.
Harumi wugu wugong gu 1s after the wugu2 wugong gu => wugu2 wugong damage = 0. Harumi wugong starts doing damage.
Fletcher A damage: always on because no debuff.
Damage ranking:
place # 1 fletcher
Tied 2nd place competition: wugu2 & harumi wugu
Now 3 wugushi + 1 fletcher vs boss.
Wugu2 uses needle blow & wugong gu & pot on Boss.
Wugu3 uses Needle blow & wugong gu & pot on Boss => wugu2 damage = 0.
Lastly, Harumi wugu uses Needle blow & wugong & pot on boss => wugu2 dmg = 0, and wugu3 dmg = 0.
Fletcher constant damage.
Damage ranking
place # 1 fletcher and harumi wugu
wugu2 and wugu3 0 dmg, so no rank.
So the wugu using the skills last, will win in damage.