I don't really comment on the viability of a lane, but every once in a while I come across a lane that works really well. One of these is Ezreal and Leona.

First off, Ezreal is a skillshot based chamion, which means that he does a ton of damage IF he lands his skillshot. This is great, because with Leona, the enemy is stuck in one place for a long period of time.

As for Leona, Ez is one of the few Ranged AD champions with the mobility to keep up with her gap closer (the other being Graves). In addition to this, has great burst damage early and scales WITH her (they scale at approximately the same rate).

These factors, combined with Leona's passive and her omg wtf long range ult, means that Leona and Ez can just dominate the lane.

Pre-level 6, just play passive, once you hit level 3 or 5 (depending on how strong their lane is) you can start trying to kill them, shield, zenith, stun.

After level 6, the lane is practically won. Ward to protect against ganks (warding is a pre-requisite for aggro lanes, don't want to commit and get blindsided by a gank). Wait until their ranged ad goes to last hit, and slap him with Leona's Ult. Then, zenith, shield, and stun, while ez shifts in and hits them with auto's and 2 q's. That should give a least 1000 damage. If he manages to survive that and get away, then Ez just ults.