- Boosts power of Bug-type moves by 50% when at 1/3 HP or less.
- Reduces sleep time.
- Increases the power of punching moves by 20%.
Level 100 Statistics (see level 5, 50, 100)
Ledian is the best Pokemon as it is the cutest. Sadly, this doesn't mean much on the battlefield.
Switch into a Grass-type or weak special attacker and either Encore a useless setup move or start setting up dual screens. Once you've set up screens, U-turn out to the teammate that's best for the situation at hand. Roost can be used instead of U-turn if you want Ledian to stick around a little longer, since it's not like Ledian will do much with its hilariously weak U-turn if it gets hit by Taunt anyway.
The EV spread maximizes Ledian's special bulk with just 256 EVs (which is actually kind of impressive, considering), and Speed is maxed out to make sure it can set up a screen before getting nailed by an attack. Early Bird is cool for being able to switch into an opposing Sleep Powder and not be too crippled by it.
A set of Encore, Swords Dance, Agility, and Baton Pass can be used, but Ledian has a hard time setting up in most battles due to its physical frailty. If you want to take Ledian on the offensive, which I wouldn't recommend due to that atrocious base 35 Attack stat, your best bet is a set of Swords Dance, Acrobatics, Bug Bite, and Mach Punch or Drain Punch with Iron Fist and a Flying Gem.
Checks and Counters
Ledian is decently fast and so will most likely be able to set up at least one screen on any slow defensive Pokemon. Your goal should be to prevent it from getting an opportunity to actually switch in and cause trouble. Stealth Rock helps in this venture, as does nearly any physical attack. Very rarely will Ledian be the actual problem; it'll be the teammate that it brings in after getting a screen or two set up.