First off, this should be in the Official Q & A thread. Maybe I should BUMP it so that other newcomers to the Poke Center can see it.
Second, Roserade doesn't make that good of a start. There are too many Weavile/Gyarados/Salamence leads. It's good if you catch a Swampert lead, but other than that you're most likely going to switch to avoid getting KO'ed.
Roserade @ Leftovers
Timid/Natural Cure
252 Sp Atk/252 Spd/6 HP
~Leaf Storm
~Sleep Powder/Toxic
~Spikes
~Sludge Bomb/Shadow Ball/HP {Fire}
If you must lead with Rose', lead with something like this. Put the opponent to sleep, then set up Spikes. Then **** 'em alive with Leaf Storm. Alternatives are Sludge Bomb, which gets STAB but doesn't get much coverage, and Shadow Ball, which hit Psychics. Hidden Power Fire is also available for an option, as it hits Steel types that resist Leaf Storm. You could also run Toxic as another status.
Hope that helps.