Okay, it's pretty good.
First of all, I would personally use a Life Orb or Choice Specs, but an Expert Belt can be just fine to fake a Choiced set. But keep in mind it takes a decent amount of experience predicting.
Replace Poison Point with Natural Cure, altogether more useful and it can also work as you status absorber now.
Next, Leaf Storm is usually preferred due to the huge power it has.
252 SpA Choice Specs Roserade Leaf Storm vs. 144 HP / 176+ SpD Snorlax: 238-282 (47.88 - 56.74%) -- 35.55% chance to 2HKO
And that's on a Pokemon with a 160 HP and a 110 Special Defense. Yeah.
Sludge Bomb is great on this set. It stays.
For the next slot, Hidden Power Fire is better to take care of any steel types who will be resisting your other two moves. Also, the psychic coverage isn't super important as most of them are obliterated by Leaf Storm.
The last slot is a few options. Rest is recommended for Life Orbs sets as you can fully heal off the recoil and when you switch out, and Natural Cure will do it's work. Sleep Powder can also be used on Life Orb sets to cripple a foe with Sleep. For the Specs set, Extrasensory in the best option to hit certain fighting types and the occasional poison type.
The set should end up looking like this.
Roserade (F) @ Life Orb / Choice Specs
Trait: Natural Cure
EVs: 252 Spd / 252 SAtk / 4 HP
- Leaf Storm
- Sludge Bomb
- Hidden Power [Fire]
- Rest / Sleep Powder / Extrasensory
Hope I helped! :)