Ah. Bulky. Reading is good.
Anyway, way are you not using Kingdra? It is better than Floatzel (however cliched), but as for Toxicroak, Zone works but I would go with Bronzong. Bronzong is great for it, because it is very bulky, has essentially no weakness under rain, and can Explode if necessary. Scizor is still an option, and works similarly. It is also kind of weird that you have so few Water Pokemon on a rain team. Things like Ludicolo would helpa lot as well. It could take the place of Roserade.
I hope that helps, even if the first didn't.
Well, the team was cobbled together from stuff I've raised and traded for, so that limits my choices. Floatzel's the only Swift Swimmer I have as of now. Main reason for hardly any Water is that Floatzel's my only physical water, and I'm not really sure how to work special water in doubles, since Surf hits your ally and Hydro Pump is too risky for me, so there's a problem. I do have a Scarf Wailord with Water Spout (and Selfdestruct) though.
Reasons for no Kingdra are that I don't have one, I've never liked the thing, and that I can't figure out how I'd work it. Physically, other than Waterfall it only really has Outrage, which knowing my luck would more often hit the wrong enemy, and I'd have to get it out of there when the confusion kicks in. I already detailed my problems with special water in doubles, and I can't do mixed stuff to save my life.
On Scizor: Honestly not a fan. Can't work the thing, I tried once.
On Bronzong: So it gets the rain up. Then what does it do? At least when Spiritomb walls stuff it hurts them with burns and sometimes confusion.
On Ludicolo: Stalling buddy for Spiritomb with Rain Dish and Leech Seed? Or offensive? Come to think of it, a Swords Dance one could take Floatzel's spot, although it's much slower than Floatzel.
Sorry for kinda sucking at this. I've never really been good at making teams, most of the time they're just a bunch of misfits all doing their own thing. I mean seriously, the high point of teamwork in my doubles teams is the old "EQ with an airborne ally" trick.