Hey, i'm Derpyhooves! And this is my guide to AD Bot Rengar. I find this build works very well when playing against most comps. I personally have had a ~80% win chance with this. I am only Silver 5 so i am versing Bronze 1 - Silver 3 with this build. Most likely not viable in higher ranks, but amazing up to gold.

Pros

Very aggressive
Strong burst
Lane domination
Very strong at pushing/roaming afterwards
No Mana :D
Amazing gap closure

Cons

Support dependent for sustain
Weak against teams with traps (stops bush farming)
Relies on bushes to initiate / poke

AD Rengar does very well laning against ADC's, due to the fact that his passive allows him to close gaps with no cooldown (unlike any other melee champion or assassin). As long as you can stay aggressive and keep them pushed at least to the first bush you can dominate with your leap / Q combo. My fav strat is to sit at the farthest edge in the bush closest to my turret while my support sits just in front of me in their bush to bait with a ward under her. When they go to attack my support she kites them to my bush and once they get to where she originally was i leap to them and Q. Most players will run straight to their turret, which keeps them in the bushes for 2-3 more leaps and they either have to base giving me a cs advantage, or they give first blood. After this, you just need to sit in the bush and Q everytime it's off CD onto minions or their adc/support if it won't place you too close to their turret. Do this until you have built up 5 stacks on your resource bar, with 5 stacks (if it's time appropriate) sit in the bush and wait for them to come close, leap to them and Q twice for insane burst damage. Doing this repeatedly will keep them hard pressed to stay i lane, either feeding you, or forcing them to base. This also keeps their jungle camping bot lane giving top, mid, and your jungle a distinct advantage. This can pose a threat without proper warding or a strong support. If their jungle enters lane for a gank and their adc isn't close enough to engage with him or he is below half hp (or if you're overfed) you can leap to him and shut him down quickly evening the numbers in lane forcing their adc/support to either back off or fight you. If their ADC is trading well or trying to engage you, keep a pink ward in your bush and continue to run into the bush and leap out at their ADC, stopping them from engaging you due to lack of sight, and allowing you to poke them down very hard. This strategy works very well against comps that are squishy or have little cc. Against tanks or champions with CC (like teemos's blind) just play defensively. If their support is tanky, focus their ADC and utilize your passive leaping past their tank to burst down the ADC, or if you're versing a blind, or CC, jump ont he support to get the CC out of the way while your support keeps you alive or keeps the ADC cc'd