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Interesting that they suspect tested speed and defense. speed is definitively a monster that should remain in ubers, but defense? deoxys defense is great for hazards, but it's also a sitting duck, a bait for setting up. Honestly I can see it go as low as UU if it is released from Ubers.
EDIT...
Hello. This is my first day on this forum and the main reason I subscribed is because I wanted to ask a simple question. Why is deoxys d banned? yeah, it has good stats and decent support moves, but it's typing and ability are horrible. This pokemon wouldn't be that used even in OU so I wonder...