Everyone's prepared for the classic modest set these days, it just won't work anymore.
When you look at heracross' stats on smogon (which should ALWAYS be your main source of information when it comes to pokemmo) you'll notice it has quite a respectable att stat.
The most effective sets we've seen in the latest tournaments were all mixed and for a good reason: chansey
My personal favourite is:
Hasty/Mild Superpower, Sunny Day, Hp fire, Megahorn
152 spatt, 100 att, 252 speed.
Make sure you have something for gyarados too (impish breloom for example)