Here are two replays of the team in action(with LO Celebi):
I don't like Shaymin a lot as it can't do a lot against Dragon and Flying types, particularly Torn-T, Dragonite, Salamence, and Kyurem-B, all big threats. If it goes for HP Ice then Ferro sets up on us all day long, not to mention that Celebi handles better Keldeo in general, due to the Fighting resistance, while Shaymin can succumb to Specs or LO +1 Sacret Sword hits (or even get 2HKOed by Secret Sword from Scarf variants after SR and 1 LO round on Shaymin).
You definitely have a point about Timid Venusaur on sun teams. But tbh the Ttar + Keldeo and the Ferro in rain weaknesses we have right now bother me much more than Venusaur as they are more common and harder to play around. Maybe, just maybe, we could replace Terrakion with Sash Alakazam? This way we can revenge kill everything fast at least once, covering Venusaur too, and still have a good cleaner. And to cover Volcarona we can use T-Wave on Zam. So a set of Psyshock / Focus Blast / Hidden Power Ice / Thunder Wave could work maybe... Zam also helps a bit with our Gengar weakness as it doesn't need to become set-up fodder for any hazard setter in order to break its Sub (see Bronzong and Terrakion, our only pokes that can deal with Gengar). Thoughts?
EDIT: Here is another battle vs Kidogo's stall team: http://pokemonshowdown.com/replay/oucurrent4689824