Sunflora: Underestimated and Overpowered

Sunflora, perhaps the most overlooked Grass-type Pokemon of all-time, is one of the most useful Grass-type NU Pokemon in OU available. While its 30 Spe stat makes its "Chlorophyll" ability out-classed by even the likes of the paltry Bellossom, and even though its "Solar Power" ability makes it somewhat usable in OU (if you can pull off the extremely gimmicky 'Trick Room Sunny Day' team with a Heatproof Bronzong lead), its only real chance to be usable in OU as a singular-entity (i.e., no Sun and no TR support) is as a "Substitute + 3 Attacks" Pokemon.

As with almost any pokemon utilizing substitute, Leftovers is the recommended item to provide reliable turn-by-turn recovery. Sunflora in OU is no exception, but due to its pitiful Defense stat, it needs to utilize Giga Drain, which becomes its most acceptable STAB option due to its ability to aid in Sunflora's recovery while still maintaining its excellent type-coverage provided by its 3rd and 4th move-slots.

Besides Substitute and Giga Drain, Sunflora can demonstrate its near-perfect type coverage with Earth Power [which allows it to OHKO all variations of Infernape and Heatran (without Shuca Berry)] and HP Ice [which allows it to OHKO even the most bulky variants of Salamence]. The only pokemon this Sunflora set has trouble with are the Rotom formes, Gyarados, and, of course, the inevitable Blissey.

In order to use Sunflora to its maximum potential, one must have a Pokemon that can draw out Water-types in OU, specifically Swampert (due to its 4x weakness to Grass-types). Once behind a Substitute, Sunflora can OHKO many potential switch-ins, such as all OU Fire-types and Dragon-types as well as OU Electric-types. In order to support an OU Sunflora, as stated earlier, one must have a counter for Gyarados as well as the Rotom appliances. Sunflora is so unexpected that it will work more often than not as long as you cover its very few (as opposed to some OU pokes' *cough*Vaporeon's*cough*) counters.

Good luck! Here is the final analysis for Sunflora in OU:

Sunflora @ Leftovers:

EV's:
252 HP / 252 SpA / 4 Def
Modest Nature
Moveset:
-Substitute
-Giga Drain
-Earth Power
-HP Ice