http://pokemonforever.com/Thread-Warning-Traders-Please-Be-Careful?pid=201511&highlight=please+be+careful#pid201511Careful guys. If you give out a lot of dupes of the same Pokemon, reroll the PID. Looking at Ditto giveaways in particular.
Notably, I think linking to Game Link is a wonderful way to get yourself dinged as well. GL logs everything so if you start using Pokemon you didn't trade or even hatch one egg for.. probably very easy to weed out GL linked players.
My suggestion would be breed an egg, mod the egg, hatch, if you're linked to GL.