Some basic knowledge to supports when your adc is ezreal.
If you're playing an engage/tank support and you are supporting an Ezreal, it is extremely important that you do not engage while the enemy is standing in the minion wave. The minions will tank Ezreal's Qs and will remove most of his damage.
It's important to wait when the enemy is off the minion wave or it has been cleared.

(at least on this patch) and then just go full AP damage to make up for the damage deficit created by the Ezreal pick.
etc
and roam to other lanes.
The enemy mid laner will definitely not expect to get ganked by the enemy support pre6, likewise for top laner.
While ezreal can farm safely from a distance, so, you lose nothing while getting your other lanes ahead.