Heracross shouldn't even be Mid imo. It's seriously underlevelled for when you get it, the first gym he faces (Winona) is a nightmare for him, and he gets Megahorn at L53. Way too late for T/L, and without Megahorn he's pretty much fodder for them. At best, he is just -generic fighting type- until Megahorn.
Heracross doesn't get any advantage over the next few gyms he has, missing out on vital training opportunities, crucial when he comes really underlevelled. I don't really see the point in using Heracross: he was beast in other games because he came really early and can wreck things quickly with his broken stats, but almost most of your guys should be stronger than him by the time you nab him from the Safari Zone...