I got a level 100 Shiny Yanmega in a trade, and believe it or not it seems legit. However, it was EV trained differently from how I would have EV trained it. Would I still be able to retrain it?
If you can't gain Experience Points, you can't gain EVs. So, you can lose EVs by using berries, you can gain EVs from using Vitamins, but you can't raise a stat beyond 100 EVs by EV training.
Also it would help to find out exactly what EVs you had to start with, in order to work under these limitations.
in the future use the simple question simple answer thread for this kind of thing