Sylas Bot is something you wouldn't think of, but I have found it working out, since with just a simple strategy you can get the first kill easily

1. Sylas bot can be a good pick since you can easily kill the enemy ADC since Sylas has high damage and life steal with his W, any ADC cant deal enough damage.

2. Sylas can easily dodge around the enemy support and focus ADC to get an easy pick.

3. Sylas can scale well late in the same as if he was in Mid lane, so no worries about that

Pros

Can Easily kill Enemy ADC
Scales well
Easy to learn
Outplay Potential

Cons

Melee in a ranged fight
Hard to farm
Can get kited easily

Start of Game

In the start of the game you rush to bot side with your support and go in the farthest bush and camp there, make sure to unlock your E Abscond / Abduct first, when you have a clear sight of your enemy ADC focus him together with your support. This will not kill but you will most likely waste their flash. As soon as you have done your combo and they used flash go to your minions and get to level 2 as fast as possible. When you do so, unlock your W Kingslayer and rush with your E and do your full combo on the enemy ADC, that should earn you your first kill.

Early Game

This is the hardest part, you should have 650 gold and recall to get Dark Seal and either Sapphire Crystal or Amplifying Tome once you get those you can lane well against the enemy make sure to dodge skill shots and farm well if you have a good support you can engage the enemy with your full combo at level 3 and maybe get another kill. At level 6 you should either choose depending on the matchup which ultimate to take, with that ultimate you can possibly get another kill. But play safe as possible since you are melee you are an easy target to hit while farming.

Mid Game

In the mid game your goal is to either roam to help your team or keep pushing the lane, this depends on your team and match up so choose accordingly. If you are behind instead make sure to stay in lane and farm safely to catch up.

Late Game

Late game is the same as when you play Sylas Mid so nothing to worry about if you are snowballing.