Firstly, let me just suggest that you ignore the current support meta and find the champs that are the most fun for you. This will always be the biggest factor in whether you do well.
That said, one that you might overlook is
His Noodliness. As a poke support, Vel'koz also offers the slow of his Q (similar to Karma) and the knock-up on his E as valuable peel skills. His laser ultimate also has a light slow on it, but it's more valuable for the ridiculous damage potential. If any of the enemies is below ~800 hp in lane, then he can kill them with a WER combo. The skill comes in taking enemies down to just above dead so that your ADC can easily finish them off.
Laning skill comes from conserving your mana just the right amount, which means holding your skillshots until you have a high chance to hit. When the enemy is going up to last hit, get them with your WE combo to proc true damage from the passive. When they engage you in a gank, slow the damage dealers with Q and use the knock-back on E to keep you and your ADC safe. If you have enough distance from them, Ult backwards and they won't be able to follow your through the laser. Kiting is what VK is made for.
By the time teamfights start happening, you end up destroying the entire enemy team with a well-placed laser and true damage passive procs, none of which depend heavily on items for doing damage.