Ferrothorn needs some kind of way to set up hazards which is its main purpose. Consider putting Leech Seed or Stealth Rock on the set and it'll be much more effective. Poison Jab is also kinda useless because you don't really have a need to use it, but if you really want you can keep Curse although Protect might be of more use.
Also is http://www.pokecommunity.com/showpost.php?p=6524881&postcount=6 what you mean by formula?
I was doin research on that thinking the same thing. It doesnt naturally or TM learn Either of those moves,It looks like spikes is an egg move. I will look again.