Roserade

Every Roserade has its toxic thorns and razor sharp leaves, apparently. Roselia was once ubiquitous but useless, but its evolution justified the hassle catching them once Roserade finally took center-stage. While not the titan of the type that it once was, Roserade is still a powerful Pokemon that can help out if you're short on Grass Types or want Poison coverage for that one raid every 5 years where Poison is actually optimal. 

Best PvE Offensive Moveset

• Magical Leaf and Grass Knot is an objectively great Grass Type moveset, and definitely Roserade's best.
• Poison Jab and Sludge Bomb is the way to go if you want Poison damage.
• Razor Leaf, Bullet Seed* Solar Beam, Leaf Storm, and Weather Ball Fire* don't offer any value to Roserade on offense.

Best PvE Defensive Moveset

• Magical Leaf is Roserade's strongest Fast Move on defense, with Poison Jab as a secondary option depending on the set.
• Weather Ball Fire* has good counter-coverage and comes out frequently, making it arguably the best Charged Move for a defensive Roserade.
• Dazzling Gleam has great neutral coverage and power, making it a great move option as well.
• Sludge Bomb has good power and comes out early, but is pretty widely resisted.
• Grass Knot is Roserade's best Grass Type Charged Move for defense.
• Razor Leaf, Bullet Seed*, Solar Beam, and Leaf Storm are all lesser versions of the above moves on defense to varying degrees.

Poison Jab is the preferred option, being above average in both DPT and EPT. Bullet Seed offers greater energy generation, but the loss in DPT is often not worth it. Magical Leaf trails slightly behind Poison Jab, though it does offer Roserade a more consistent source of Grass-type damage. Razor Leaf turns Roserade into a ferocious unshieldable source of Grass-type damage, but it has to compete with Victreebel for that kind of role.

Weather Ball Fire is a move limited to Elite TMs and specific events like Community Day, but is highly recommended due to its low energy cost and efficient Damage Per Energy (DPE). Grass Knot and Sludge Bomb require the same 50 energy and deal respectable STAB damage, and either can be chosen depending on the coverage needed. Leaf Storm costs slightly more energy, and is considered a higher risk vs reward play. Dazzling Gleam and Solar Beam demand way too much energy to use consistently.