Pokemon Black Version 2

Are you sure it is your Hydreigon the one causing you trouble? Just to eliminate other possibilities.

yep, i tried putting my team into the GTS, only hydreigon couldnt go in

i guess you could try renaming it just to see if that helps. Thats the only idea i can think of

Do you have another Pokémon using Life Orb?
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"If you want to know what a man's like, take a good look at how he treats his inferiors, not his equals."
-Sirius Black