Not sure whether this qualifies as creative or new, but what the hey. I've been using it with decent success. I'm fairly new to all this, so please don't rip into me if it's a common set. ^_^
Sleepsweep
Roserade @ Life Orb / Leftovers
Hasty Nature (- Def, + Speed)
EVs: 4 HP, 252 SPA, 252 Speed
Sleep Powder
Energy Ball
Sludge Bomb
Shadow ball / Hidden Power Fire
This set is designed to take advantage of Roserade's mammoth Special Attack Stat and decent speed, providing good coverage and status support. Sleep Powder allows you to sleep an incoming counter and either whittle it's health down or switch to your own counter. Energy Ball does massive amounts of Damage to any Rock/Ground/Water type that doesn't resist it; even Tyranitar is not safe from a 2HKO in sandstorm. Sludge Bomb does huge Damage to Celebi and Shaymin, while Shadow Ball allows it to come in on Gengar's Thunderbolts directed at pokemon weak to it and threaten an OHKO. This set is walled by Steel types, but again Sleep Powder allows you to incapacitate them as they switch in, then sound the retreat. If Steel types concern you, HP Fire is a viable option over Shadow Ball, but note that Heatran will still wall you. If you do run Shadow Ball, this is best paired with a Magnezone to trap and kill Steel types that seek to wall you.
EVs are fairly simple. Max speed and hasty allows Roserade to outrun all max speed neutral natured base 100s that are not carrying a choice scarf, and at worse force a speed tie with other max speed positive natured base 90s, like Porygon-Z. Max special attack gives Roserade a special attack of 349 even on a neutral nature, with the remaining 4 put into HP for good measure.
The choice of held item is entirely down to how you want it to play; if you feel that you need more power at the expense of durability, Life Orb is the way to go, allowing Roserade's dangerous STAB attacks to do serious amounts of damage to anything that doesn't resist it. If you feel that more Durability is needed, use leftovers, as 80 and 90 BP STAB attacks coming off a base 125 special attack are still nothing to be scoffed at.
Damage Calcs
All calcs are assuming Life Orb.
Energy Ball Vs Max HP / SDef Hippowdon : 77.86% - 91.43% - Easy 2HKO with Leftovers factored in
Energy Ball Vs Max HP / 128 SDef Tyranitar : 73.51% - 86.39% - Easy 2HKO, even in sandstorm
Sludge Bomb Vs Max HP / SDef Celebi : 74.01% - 87.13% - Easy 2HKO with leftovers factored in
Shadow Ball Vs 0 HP / SDef Gengar : 108.43% - 127.59% - Easy OHKO
HP Fire Vs Max HP / 0 SDEF Jirachi : 48.76% - 57.18% - Possible 2HKO with SR down and Leftovers factored in (Around 80% chance I believe)
Pretty standard affair, but quite effective. Opinions?