Cilan is the Unova grass-type gym leader. He has about five of the following: Simisage, Torterra, Meganium, Serperior, and Sceptile. He has quite a couple Chesnaught, which jump off or Torterra after you defeat it. He also has one Venusaur that uses Solar Beam. He reckons that he is a connoisseur on just about everything.
Here is a large informational excerpt from Sam's blog:
(For some reason I can't paste, can someone please paste the round 3 part of Sam's blog? Thanks)
Good strategy: Mew or Celebi with AncientPower and Baton Pass, and two pokemon with Fire Blast or Fusion Flare.