Joule is the strongest support in the game currently if played right, you can dominate early game, feed your team mid game, and wreck team fights late. Joule can secure Krakens and finish off turrets fast and unexpectedly. Something kind of troll you can do if they have an open base without any turrets; Hop over the wall into their base from the jungle (you will be behind them while they are guarding) throw some Thunder Strike in there if needed then end it with a Big Red Button . As stated above, she is a tanky DPS, so its not like she cant carry her own wait in a 1v1. You don't need some carry style build to slap damage against your enemies, you are tanky enough and have enough base damage to get kills.
When jungling with someone else you should act as the CC play maker. Get your Thunder Strike first and your Rocket Leap second so you can clear jungle early. It is important to get an Iron Contract so you don't have to get last hits on jungle monsters, instead have your "carry" jungle make the money while you get 20% of the gold. Communication is important and is hard to use, but telling your carry to go lane or go counter jungle to try to get a kill is important. The new meta is duo jungle the only hard part is that you wreck your own side of jungle so you have to go into theirs or gank lane. Save your Big Red Button for ganks, counter jungles, team fights, and most of all, securing Krakens and stealing minion/Gold mines fast.
Your job when you are in lane, is to set up kills for you carry and jungle. At the same time you want to prevent the enemy team of doing the same. Joule is a tanky support, you are able to face check bushes and eat damage for your carry and jungle. If needed you can tank minions and turrets, you able to do this because of your passive that gives you 22 armor level 1 - 90 armor level 12 for basic attacks to the front of you. To prevent ganks, put Scout Trap in the bushes that connect the jungle to your lane. If they do the same, the go and eat them by walking over over them. Your Thunder Strike has a much larger range then it looks like. Use this to poke down the enemy, you can do it even when they are under turret. Rocket Leap is a crucial move that takes some practice, but after you learn movement and positioning you can lock down and engage like the bully you are.
As a support you are in charge of a couple of things. You are the engage, lock down, tank, and defense. The engage will be explained in the team fight chapter. For lock down, you use your Rocket Leap to peal (slow/stun enemies) for your team then use Thunder Strike to slow because of the item Frostburn . Being a tank is face checking, leading your team eating damage, eating Scout Trap , tanking turrets if needed. Defense is mainly setting Scout Trap in bushes and buffing, healing, pealing with Crucible , Fountain of Renewal , Atlas Pauldron . The item Scout Trap is very useful because it makes your laning faze safe, you aren't playing scared about being ganked.
In team fights are are the engage which means jump into their team with Rocket Leap . After that your job is to position yourself to get the best ult off. If you can get all 3 enemies in one ult you have just won that team fight. Your ult Big Red Button is a melter that is game changing.
The three bushes to keep mined
These three places need to be Scout Trap constantly and need to be face checked to get rid of Scout Trap so your jungler can gank. The high bush in lane does not need to be Scout Trap as much, only if their support is hiding in it then engaging from it.