Moves
Leaf Storm is Sunflora's strongest STAB move, but it lowers Sunflora's Special Attack after being used, leaving it susceptible to becoming setup fodder. Giga Drain is an option over Leaf Storm, as it lets Sunflora regain a bit of health, is fully accurate, and doesn't drop Sunflora's Special Attack, although it loses out on a lot of power. Earth Power allows Sunflora to take on Fire- and Steel-types a bit better, such as Rapidash and Probopass. Hidden Power Ice allows Sunflora to take on opposing Grass-types, as well as Flying-types. Hidden Power Fire allows Sunflora to hit Ice- and Grass-types for super effective damage. Sludge Bomb can be used to deal more damage to Grass-types such as Tangela, as well as Fairy-types such as Mr. Mime. Synthesis is used to restore Sunflora's HP.
Set Details
The given Speed EVs allow Sunflora to outpace the likes of Audino, Prinplup, and unboosted Klang, while maximum Special Attack EVs paired with a Modest nature allow Sunflora to hit as hard as it can. Sunflora's HP investment grants it a little more bulk. Life Orb allows Sunflora to deal more damage with each attack, albeit while losing a bit of its health. Solar Power is only useful under sun, allowing Sunflora to hit even harder, although it wears it down fairly quickly in combination with Life Orb.
Usage Tips
Most of the time, Sunflora should use Leaf Storm if it wants to severely damage a foe, although it has to be wary of being made setup fodder after the Special Attack drop. When possible, use Synthesis to recover Sunflora's health, as Sunflora can easily be weakened by a combination of Life Orb damage, residual damage, and opposing attackers. Sunflora should be brought onto the field by a slow pivoting move such as Probopass's Volt Switch or Pelipper's U-turn. If you predict a Fire-type to switch into Sunflora's Grass-type STAB attack, Earth Power can be a good option to take the incoming foe on, although if you predict wrong, Sunflora can be taken out or severely weakened. On the same note, if you predict a Grass-type to switch into Earth Power or Leaf Storm, Hidden Power Ice or Sludge Bomb can be a good option to take them on, although this comes with the same risk.
Team Options
Volbeat, Golem, and other sun setters can use Sunny Day, activating Sunflora's Solar Power and making it a more effective wallbreaker. Sawsbuck, Leafeon, Weepinbell, and other Chlorophyll users pair well with Sunflora in weakening an opposing team while sun is up. Entry hazard setters such as Roselia, Crustle, and Clefairy can break foes' Sturdy and Focus Sash with their entry hazards and can weaken incoming foes in general. Pokemon such as Regice, Sawsbuck, and Ninjask appreciate Sunflora's wallbreaking under sun to clean late-game. Rock-type Pokemon such as Golem and Probopass can take on Flying-, Fire-, and Ice-type Pokemon, which can deal severe damage to Sunflora. Electric-type Pokemon, such as Raichu, Rotom-F, and Zebstrika, can take on Flying-types for Sunflora and offer momentum to it by using Volt Switch. Zebstrika is an especially good partner, as it counters Jumpluff by virtue of Sap Sipper. Entry hazard removal from Vibrava, Pelipper, Vullaby, and Armaldo can keep pressure away from Sunflora. Grumpig also has the ability to take on Fire- and Ice-types by virtue of Thick Fat.