Hey vp,
Yesterday I created a thread trying to know the better way to give my forretress 0 speed IVs and some of you guys gave me suggestions. Then, I discovered an easy way. In Cyllage city, a man want to trade his steelix named "Thumper" for a luvdisc and his steelix have 0 speed IVs. So it is possible to give pokemon like forretress and ferrothorn 0 speed IVs through chain breeding. Guess it is a hidden present by gamefreak.
I hope this helps someone and would like to thank vp for the help. Hope you are having a nice weekend.