Run Yache Berry on Dragonite. Without immunity to sandstream, and a weakness to Stealth Rock, there is no reason to run it. Even if you are looking for the power, Yache Berry allows you to DD one more time on average, therefor the more powerful option is actually Yache Berry.
Without Rest Suicune is absolute fail. The reason it is good is the ability to use Calm Mind and then Rest off the damage, possibly using Sleep Talk to hurt Phazers like Skarmory or Weezing with Surf, or just wasting their PP with Pressure. That Suicune can't do anything, besides maybe get a surprise KO due to Mirror Coat, which isn't reliable as after a CM they will be hitting your lower defense stat, which BTW is low without Rest as Garchomp 2HKOs, SpecsMence 2HKOs, Rhyperior 2HKOs, Lucario 2HKOs, Dragonite 2HKOs, Tyranitar 2HKOs, etc.
EDIT: Oh yeah, Milotic is the most beautiful pokemon in the game, and Suicune is quite ugly.