[X] Disallow the Set Up - Send in Umbreon and use Taunt. After this, a combination of Dark Pulses and Hyper Beams will allow for an extended range engagement that should be to Umbreon's advantage.
[X] Face the Gym Week 45 - Adding a few days to train may be worthwhile even if you can already win. Plus it'd allow you to see which Pokemon Willow finds.
[X] Bait out Explosion - Send in Dragonite and attack aggressively (without using Outrage). The instant Koga uses Explosion, use Protect then continue the battle.