In ranked, this is still very effective as Ad gragas counters common picks such as Renekton or Mundo.

You need to pick up your w second, this will boost your trading ability in lane and overall damage.

During the laning phase, It is important not to waste too much mana. The flask may help with this, but honestly it doesn't fix all your issues. After pushing the enemy out of lane w->e the lane to push it out to the turret. Ad Gragas is a very effective pusher and good enough cser to not give you any excuse to miss more then 10 cs during the laning phase.

Ad Gragas is an amazing duelist and split pusher, his teamfighting potential is not very existent besides being cleanup material. His ult still does good damage and breaks the enemy apart allowing him to be somewhat useful during the teamfight, his natural tankiness allows him to get to the back lines and deal a good amount of damage to the carries.

This is not a troll build, it does work and simply takes a little practice.

If you are ahead, feel free to pick up a rage blade. This is just a good overall item on Gragas and can nearly double his damage output.