Possibly THE most solid team I've seen on here, awesome ! Stall's fairly uncommon, now, but I've just started using it for the first time in BW. You don't have huge problems, 3 of your pokes arn't affected by T spikes, and you have solid counters to pretty much all stallers, Hydregion is an awesome counter to some big threats as mentioned.
One problem I can see is a SS Cloyster, it can outspeed your entire team, with Super effective coverage on 4/6. He's fairly uncommon and to be honest dealing with him shouldn't be too hard, Scizor's a pretty solid counter outside of rain, Kingdra can also set up on him. I only mentioned because there's literally nothing else I could think of that can cause trouble to your team.
How does the side function outside of rain ? You've got such good defensive synergy I'd imagine it's pretty good.
Luvdisc'd for this one !