Hey, I'm banewastaken, I like playing a lot of off-meta adc's and I'd love to show some people how I like playing them, and the stuff I've learned from playing them! Hope you enjoy the guide and that you found it useful. Kennen's early game damage might not be the best in long trades or all-ins (without the right support) but if you abuse the HOB + Q + W trade everytime it's up, you can put up extreme amounts of pressure.

Kennen is very short ranged, so you're gonna try to avoid picking him versus long range adc's. Besides from that, you're mostly picking him for the CC, if you see that your teamcomp lacks CC, and that there is a champion that gets heavily countered by CC (Katarina, Samira, Master Yi) you can pick him here.

If you have an all-in support, you should be looking for short trades with them, procing HOB, Q, and W, and leaving before they can retaliate. My advice: limit test. Try to see what matchups are easier to trade into than others. Some red flags are Lucian, who can do a lot of damage as soon as he gets out of the stun if you couldn't get away.

If you have an enchanter support, farm it out, poke with Q. Not a high interaction lane.

Skirmish as much as you can if the enemy is not ahead. Your ult has some insane teamfight power that you need to be putting to use to get your team and yourself ahead in dragon fights. Kennen adc prefers to be the second man-in so he doesnt get focused down and bursted, but if you play it well, you can initiate fights yourself (specially in the mid-game, where champions dont usually have enough damage to burst you down).
Again, one of the best advices I can give is to limit-test and see into what teamcomps you thrive. Red flags are hard disengage champs like Alistar, Gragas, and Janna.

You are a major threat to the enemy team, you can put out an exponentially amount of dps AND engage/disengage for your team with your ultimate. Try not to die, with your low range this may be hard, but you need to wait for the enemy team to use the abilities that are a threat to you. Hit the tanks, and look for good ultis. If your tank dives into the backline, judge if its a good play, then follow up or not. Don't take 1v1s. You will lose against most people and most times gain nothing, use your teamfight power to, well, teamfight.