Is it Possible that your own Pokemon can lose some of it's own Stats?

Question

While I was Training My Brother's Rayquaza and My Giratina, Something happend to my Giratina.
It appears that my Giratina lost some of its own Stats. when it Leveled up and it doesn't even have a Pokerus.

The Stats. that it have was This:
Hp +5
Attack -17
Defend +2
Sp.Attack -11
Sp.Defend +1
Speed -6

Comments

GREAAAAAAAT QUESTION!!!

Answer 1

You/he Must Have Used Speed and attack Reducing Berries. Either That or You Misread it. Thats The Only Logical Explanation.

Comments

You see it that way, but I have never use anything on it the only thing I gave it was the GRICIOUS ORB plus I cought it on Platinum and instantly Trade it to Heartgold, then 2 level ups, and now This happens.

I didn't even Know that they can lose their own Stats. until now.    8^(

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Well, cool mystery:))

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Thanks DarthDestiny, but this was one of the Most Messed up way on how to Discover this.

For once I Wanted someone to do this first, but I turned out to be the First and not only that, When I discovered this messed up Mystery, a Pokerus hit my Brother's Rayquaza from out of nowhere.

The truth is that even though my Giratina lost a little too much Stats. without the Pokerus, my Bros. Rayquaza ended up having it instead, even my Giratina was Jelouse of my Bro. Rayquaza.
[Giratina: >=^( ]