Jarvan, as I have played in LOLph server has always been used as a tanker-iniator.
But not for me, because it frustrates me to see a cool-looking hero all buffed up yet unable to kill enemy champs. So this guide will give you an idea how much Jarvan IV can do in 5v5 battle.

The runes I alloted for Jarvan is actually for a tank-DPS, giving it huge armor penetration, extra armor and magic resistance on early game.

When playing 5v5, I usually start with Doran Shield for a HP and armor buff early game.

While laning, you try to kill enemy champs at level by doing a standard combo + lane mate + ignite. Early game kills can build up some tough cash for you to buy a B.F sword. BF sword will give you an AD buff on both standard attack and skill damage specially on Dragon Strike. After this, make sure to build a mercury treads to give you a little bit of magic resist and tenacity. Then, you can continue completing you Black Cleaver for Dmg Burst.

Choosing your first tank item will depend on your enemies when majority is physical damaging, go with Thorn mail, when magical damaging, go with force of nature.

The rest of the items are as shown in items view.

My summoner spells are Ignite and Clarity. Ignite helps you in killing heroes specially those who are running. And I always use clarity for lane control and skill harass.

Pros
-Very good CC skills
-can act as semi tank
-can act as dps
-good initiator skill
-good escape skill
-cool sprite
-cool ulti shout

Cons
-delay in ulti block skill cancel
-and yeah jarvan is melee (is this really counted?)

Jarvan has perfect skills for farming. Early game you can use his innate skill to last hit creeps and as you grab a BF sword you can probably kill creeps with your standard combo.