This is the now the most disappointing moment of my Pokemon Y history.
I got dubed. I got scammed. I got tricked.
I'm furious at myself for being so stupid.
So some Passerby (who I thought I had on my friends list, mistake #1) asked me to trade. He offered a Haunter, but I already have a Gengar. I offered other things but he was adamant about getting rid of this Haunter. So I thought, another Gengar can't hurt, right? So I gave him one of my many Rhydon, Pokemon got traded, Haunter evolved, all is good. Then he tried to trade the Rhydon back, which made me think "Ooooh, he wants a Gengar, that's why he wanted to trade Haunter so bad" so, being the nice guy I am, sent his Gengar back.
Here's where I got stupid.
He put up his Level 51 Xerneas, so I, thinking he needed help filling his Pokedex, put up my Level 100 Yveltal. Needless to say, he did the trade, then refused to give back my Yveltal.
Xerneas has 4 IVs, compared to my Yveltal's 3 IVs, but I spent a lot of time getting it to Level 100 and I really like Yveltal's Oblivion Wing, so needless to say, I feel ripped off and scammed, and I can't believe I was that stupid. Since I thought he was on my friends list, I got lulled into a false sense of security. Dammit.