Venusaur is the undisputed King of Starters in my book. I don't care that he isn't "Uber" like Blaziken, he's still the coolest of them all.
Speed Boost Blaziken and Contrary Serperior shouldn't be counted, just like a starter shouldn't be counted with Wonder Guard. Those abilities are horribly broken, and the only reason other pokemon aren't broken with those abilities is because they have critical flaws (Ninjask has horrible stats and already amazing speed, Sharpedo lacks a boosting move, and Spinda is Spinda).
In other words. You are right, Venusaur is the king of starters competitively.
Not changing this sig until we get a new main series Tales game released on a Nintendo console in the US