What counters a fed fighter?

Kiting

Well kiting doesn't work on jax with his gap closer

He'd just hop and decimate karma, gnar and kennen

Absolutely nothing.

Fed ADCs or mages are still easily killed. Fed fighters have no counter because not only do they destroy everyone they are also tanky af

You have to hope hes dumb and jumps in 1v5 without waiting for his team and you need all 5 people to focus him

A kiting adc

champions that can keep their distance and still do damage, preferably with a slow or stun

basically anyone that can poke from a distance without having to commit

1v1 An even more def mid/adc.

Proper kiting and dragging the game out. Being fed is an advantage that falls off as the game goes on and people get their full builds, and fighters are a lot easier to kill in the late game because of all the damage flying around.

Death.

Skill.

the unfortunately cowardly tactic of kitting other then that do not know