I got a Vulpix with Drought and a Shiny Level 100 Gourgeist through WT a little while ago, but my Y was corrupted a few days ago, and I lost everything. I had a few shinies, my X and Y Charizards, my Eeveelutions, and my attempt at filling my dex was shot to hell....I'm still trying to recoup my losses through my X.
To prevent loss of pokemon when a game corrupts you should use the pokebank its a lot less likely for anything to happen to your pokemon in the bank than on you game although items will still be lost.