An interesting tactic that no one has mentioned yet is Wide Lens. Yeah, it sounds gimmicky, but it boosts Leaf Storm, Glare, and Leech Seed's 90% accuracy to a slightly more respectable 99%. This means that all those 1/10 misses on Leaf Storm (and also Glare) that can prevent a quick KO and +2 become much rarer, 1/100. Without defensive investment (and even with), Serperior could care less about Leftovers recovery, so it's not losing a lot when running Wide Lens.