Balancebreaker

Hello I am sorry to disturb you but I have encountered a bug. So i finished the Johto Liga and wanted to Hoenn, before i can go there i have to train a rattata to level 80. Not so hard I thought and started training, after a while i gave my rattata to a friend of mine so he could train it a little and give it back to me. Problem is that the "OT" Field is now empty. Not my name, not the name of my friend it is just blank. And now the Kid says "This isn't your Rattata" .. but it is. I don't know what I should do because I don't wanna train another Rattata to level 80 (it was quite an adventure). My friend and I often trade pokemon and this has never happened. I hope you can help me. Best Regards, Alexander