There is no single Pokemon you can switch into Venusaur initially because of the possibility of Sleep Powder.
Hypno and Noctowl :D
But really, Venusaur's very not-broken. I'm seeing people basically saying that it's broken because it can go physical or special. The most appropriate response to this is WTF? Altaria can run both at the same time (oh, wait, Altaria's broken...), Blazkien can go either way, Arcanine, Raichu, Ludicolo, Sharpedo...
Seriously, guys. Sleep powder =/= broken, the ability to run a crappy physical set along with a special set =/= broken, a special wall that gets OHKO'd half the time by an unboosted NP Doom's Fire Blast without entry hazards =/= broken.
Edit: going past my knee-jerk reaction and actually reading the noms, they do bring up some valid points - probably the best being that Venu's counters are all pretty much sr-weak, but no spinners can really stay in on Venu. But IMO they're also basically saying to vote it BL because it has Sleep Powder...