Sun Offense has always occupied a niche in bw OU tournament play. Against players who favor weatherless offense or rain offense, Sun is a good choice because it has decent match-up against these two and does passably if they choose to use a frail variant of Sand offense. SO if you expect your opponent to use offense, Sun is a strong choice to avoid an unfavorable team match-up. However sun really can never escape from it's problems with Dragon type pokemon, Dragonite, Latios, and Garchomp essentially ascertain that one of your pokemon will die every single time they switch in. In addition, any balanced Sand team will dominate the weather war unless they misplay and get caught by Dugtrio. Finally the glaring problem of Stealth Rock weaknesses mandate the use of magic bounce pokemon, or else reliable Rapid Spinners that ruin any sort of offensive flow. Anyway, in my opinion the best Sun abuser is Darmanitan because it OHKO's everything with flare blitz, and with U-turn it can allow dugtrio to catch opposing weather inducers leading you to an easy victory: Darmanitan@ Choice Scarf Max Attack Max Speed Jolly U-turn Flare Blitz Super Power Fire Punch It OHKO's Terrakion and Latios with Flare Blitz, in addition to anything that doesn't resist Flare Blitz. And it doesn't have the problem of V-Create where your speed gets lowered after you ko something, and it isn't weak to pursuit and has better attack than Victini.