Jinx is the quintessential hyper carry who can output incredible damage from long range but is incredibly vulnerable without protection. Lulu is a fantastic support to pair her with, as she can enhance Jinx’s damage and protect her from harm.
Fishbones -- Jinx’s rocket launcher -- is pretty good at pushing waves in the early game, as its long-range and splash damage allows Jinx to attack multiple minions at once from a safe distance. It can also be used to chip away at enemies, along with Jinx’s W. Attacking with Jinx’s minigun (Pow-Pow) grants her a stacking buff that increases her attack speed, which persists even if she switches over to Fishbones. Therefore, once you've generated some stacks, Jinx can switch over to Fishbones to fire off multiple rockets quickly with increased attack speed. Jinx’s E should be used to protect yourself from incoming threats, to trap enemies who are out of position, or can act as follow up CC.
Meanwhile, Lulu’s kit revolves around decision making. Her E can be used to either poke enemies or shield allies, while her W increases an ally’s attack and movement speed or polymorphs and slows an enemy. In the laning phase, E can be used in combination with your Q for the poke damage, or to shield you or your ADC when you’re taking damage. Generally, W should be saved to CC aggressive enemies in the laning phase as increasing your ADC's attack/movement speed isn’t too valuable in the early game when they don’t have much AD.
Though Jinx won’t adapt her playstyle too much when paired with a Lulu, Lulus should focus on protecting and buffing the Jinx. Her E should be used when Jinx is trading with the enemy bot lane to reduce the damage she takes and increase her damage. How you use W will depend on the situation - if an enemy is attacking or diving Jinx, it should be used on that enemy to keep your Jinx safe. However, if Jinx is relatively safe and free to damage the enemy, it should be used on your Jinx to increase her damage and mobility.
Lulu’s ultimate is another protection tool for Jinx, as it increases health, knocks up nearby enemies, and causes nearby enemies to be slowed. Given Jinx’s long range, it’s unlikely she will be close enough to enemies for Lulu’s ult to be used offensively. Instead, it should be saved to save the Jinx when she is being dived from melee threats or being CCd, as it will increase her health and interrupt the enemy with an AoE knock up.
Items and Runes
Lethal Tempo is an excellent keystone on Jinx, as she already has increased attack range when attacking with Fishbones, so the two combined allows her to stay safe while attacking enemies from a great distance. Jinx can opt into either Galeforce for the mobility or Kraken Slayer to shred through targets, and build other standard ADC items like Infinity Edge, Rapidfire Cannon, and Guardian Angel.
Meanwhile, Guardian provides Lulu with another way to protect Jinx and can be procced if you use your W, E or ultimate on an ally. Though Revitalize increases the strength of your shields, it can be switched for Unflinching if you’re against a team with a lot of CC. Shurelya’s Battlesong works incredibly well on Lulu as it can be procced from casting your W or E on allies, and grants you both a ton of movement speed over the course of a game. Other than that, standard enchanter items like Chemtech Putrifier or Ardent Censer should be purchased.
Jinx and Lulu are all about dishing out absurd amounts of damage from afar, as Jinx’s long-range basic attacks shred through enemies. Meanwhile, Lulu can increase the damage from these basic attacks and keep the Jinx safe from any threats.