for example vs a late game fiora, akali, leona, lucian, lee sin?
I really dont know what to do in situations like this as an ADC because everyone I am targetting is a bad apple. So how do you deal with this? Shut them down early? Have loads of CC? Pick orianna or ziggs?
Linna Excel2 votesHope you have a fed Poppy with a GA.
youngjake931 votesUm if you need to win duels as an ADC you might want to go BORK+BT+resistance item/frozen mallet. 30% lifesteal+tankiness can actually allow you to 1v1 some assassins like Zed if you are fed. It generally lowers your backline carry potential by a lot, but if you NEED to 1v1 then that's what you do.
TekkenPlayer1 votesI think I can outplay many bruisers (udyr, fiora, yi, pantheon, vi) or assassins (only Zed XD) but against a well coordinated team I felt so useless because I couldn't carry hard enough.
Dueling is fine to me. Its really how to deal with high burst comps at late game in team fights..
Quepha1 votesbuild a GA play an adc with a dash of some kind try to stay safe in fights. you won't contribute too much damage if you're doing what you need to do to stay safe, but you also aren't providing the enemy a target to dive to, assassinate, and pivot off of in their team fight. i recall playing a game as ashe against a similar team and by using flash + my ult + help from my team and staying way back i was able to make their assassins overextend so far to kill me that my eventual death was a pyrrhic victory for our team because they could collapse on the enemy team who's members were now all crazy out-of-position.
i think the concept of a "pyrrhic victory" is really important to understand when playing sustained damage champions (glass cannon adcs or tanky bruisers) because the threat of what you could do provides more help to your team than what you actually will do because of how it changes the behavior of the enemy. you draw a line in the sand and say "you better not cross this or i'll smack you sooo hard" and the enemy just doesn't cross the line, but forcing their movement and zoning them off is powerful even if you don't rack up epic k/d ratios.
crippler381 voteshmm, 
since the damages, or for real you could 
and use the active to get rid of cc, other than that lifesteal and GA, also staying away from fiora, akali you should be fine against if you have someone to peel or are draven, lee sin is the same thing unless the guy is just too fast and insec kicks you, Lucian, well you should be able to kill Lucian, in a teamfight I would say just wait until the cc is blown if you can and then start blasting them if you're koggles with your redonk ranges, or if you're vayne try and make clever use of your invis tumble to keep them away, or if you are um... darn who is another hypercarry... oh right twitch, twitch looks like just position well and unload on them, use your blade of the ruined king on fiora since all the others can just get in real close real fast and run away if you have to, but generally I would think you should try and eliminate the assassins asap, just a thought. Sorry it's not much help