Shazam isn't what he used to be awhiile back, but he is still a decent jungle pick. Also remember to count to 3 when using your skills. Every third skill is in empowered. Your ult may not be empowered, but it will count as a charge to it. 

Why Shazam on Coast City?: Shazam is a solid pick for Coast City because he has a good jungle clear, and unique crowd control. He is also a solid split pusher when it comes to mid and late game strategy. The best reason he is a great pick for Coast City is his Ultimate. You can disable a whole team when ulting into a teamfight.

There is a jungle explanation attached in with my main Coast City guide. If need any info on Coast City, it is all there. 

Start the game with Mar RIng T2 and 3 health pots. If you decide to take super strength instead of Psy Assault, remember to use it to help invade. Leave Mar ring at T2 and immediately build Ruby of Life up to T3. Once you get it, build your modded armor items in the order you need to in order to counter the enemy team. once done, build up Oa gambit for the double damage boost you will get from it in this build. 

Now build the optional items you want/need from the optional list. With the reintroduction of a high damage ratio on his ult, PD may not be a bad thing to build on him, but only do it if your team composition allows for you to further experiment.

When ganking, lead into it with your Empowered Q when the enemy is fully commited to attacking your lane. You must hit them, or you will have wasted your time. Once they are stunned, you have Psy Assault, and your empowered E (you get it up after 2 skills) that will slow their escape enough for a high damage carry to focus them out a good amount of the time early game.

Team Fights: I would begin the fight by using your empowered Q to stun the most of place squishy. I would then W, activate your helm and ult in. I would then instantly use E to slow any chance of escape. As long as your team knows how to react to this sudden burst of CC, it will result in a fast enemy team wipe in a 5v5.

When using your ult, strike as many enemies as possible to cease a lot of damage onto your team for a decent amount of time in a teamfight.

I hope you enjoyed this guide, and that you have much luck with him on Coast City. Shazam is a major underdog pick that can be amazing when played right.