Jarvan can gank at level 2 once he’s unlocked his Q and E. Be aware of this as he may try to cheese an early gank in the mid or bottom lane.
Jarvan is really good at ganking in the early and mid-game. He will be looking to gank a lot, so it’s important that you try to equal his gank pressure and gank as much as you can to prevent him from getting his laners ahead.
He has rather good Dragon and objective control. Make sure you keep major objectives warded at all times so you can spot him before he secures the objective.
In team fights, Jarvan IV will look to lock down as many champions as he can with his Ultimate R. Make sure you’re grouped as a team but not grouped so close together that he can lock everyone in his Cataclysm R.
Jarvan’s gameplay is not very creative when it comes to fighting. Warding basic areas like bushes or chokepoints will likely spot Jarvan before he gets the chance to flank or gank.
If you can interrupt Jarvan in his combo at the start of the fight, it will be very difficult for him to get his Ultimate R off or escape after engaging. As soon as he runs towards you, either disengage or lock him down with CC.
It’s not impossible for Jarvan IV to gank at level 2 once he has unlocked his E and Q.
Once Jarvan hits level 6, his kill pressure increases a ton as his Ultimate R is really good for ganking.
Jarvan is good in the early game and good in the mid-game too. The more gold he gets, the more he can do and the tankier he will become. Keep in mind that he will continuously look to gank in the early and look for fights in the mid-game.