Speed Boost may be an absolutely fantastic ability, and a rare gem for a specially-oriented attacker, but Tinted Lens is a great ability too, and doesn't get enough respect if you ask me. With it, you pretty much have perfect neutral coverage on everything because NVE moves now do regular damage, unless they're a 4x resist or an immunity. That's also a huge boon when you want to run a Choice item, because you can't just switch in any old resist and force Yanmega out.
Too Many Lenses
Yanmega @ Choice Specs
Ability: Tinted Lens
EVs/Nature: 4 Def / 252 SpA / 252 Spe, Timid
- Bug Buzz
- Air Slash
- Giga Drain
- HP Ground / AncientPower / U-Turn
You probably will never see this set outside of UU due to its low speed tier relative to OU attackers, but it's quite effective in lower tiers where it can outpace more threats. With this movepool and Tinted Lens, you can hit just about everything neutrally. Since 4x resists to Bug and Flying are fairly rare, you can spam your STABs most of the time for at least neutral damage. Bug Buzz does a bit more damage and breaks through subs, but Air Slash has that incredibly annoying flinch chance. Giga Drain hits a few bulky threats for 4x damage, such as Rhyperior and (Mega) Swampert, and can keep Yanmega healthy. The last slot is a toss-up; with Tinted Lens, you don't need coverage as badly as on other sets, but no one option is entirely useless or perfect to complement Yanmega's moveset. HP Ground is nice against some Steel- and Electric-types, AncientPower is nice to have for Flying-types, particularly Fletchinder, and U-Turn is nice to get out of there, although its power is low even with STAB. This set still suffers from low defenses and a 4x weakness to Stealth Rocks, and now it's slower, but it does wallbreak decently in UU, and regardless of all else it's very difficult to switch into safely.