I've been thinking about this, and I think heracross should be moved from A+ to A. Heres why I think that:
Going off the definition set for A tier "Reserved for Pokemon that are fantastic in the UU metagame, and can sweep, support, or wall significant portions of the metagame. These Pokemon require less support than most others to be used effectively and have few flaws that can easily be compensated for when compared to their positive traits."
Heracross suffers from lack of priority, which to me is a flaw, because its speed tier is kind of meh compared to what else outspeeds it. Those being jolly arcanine/crobat/alakazam/staraptor/typhlosion/timid yanmega/siglyph/timid rotom heat, I'm sure I'm forgetting some, but you get the point. Now those are not great direct switch ins on heracross, however they all work well to revenge kill it, or at the very least make it switch out, something heracross does not like doing, even more so if there are hazards on the field.
I'll break down the 2 most used sets I see currently, which is scarf and flame orb
Scarf-It suffers from the same thing every scarf pokemon does, and that is if you don't predict well, it can get hardwalled. However, it still puts in some work against a lot of walls, nearly always forcing a sack or a switch.
With that being said, you can still outstall it with jelli/vaporeon
Flame orb set- This set, is like any other heracross, if brought in correctly will force a switch, but you get the added bonus of potentially getting a swords dance off. The downside to that is if the opponent switches in a faster pokemon, you have to either sack or switch out. Heracross also suffers from a lack of reliable recovery, and after a while the flame orb ticks start to add up, enough to the point where most priority users will be able to kill it
With all that being said, heracross is still a great pokemon, and it does it's job well at being able to force switches and sacks, but it has its flaws, most notably being it doesn't like to switch in often if hazards are on the field, because the combination of flame orb and hazards adds up after a couple switches.. Ontop of all that, UU is pretty hyper offensive right now, with sun teams/screen teams running wild, there is a lot of priority and faster pokemon floating around that make it difficult to utilize it to its full ability. I don't believe heracross is a 1 stop shop kind of pokemon, and should be bumped down a notch, maybe even in the current UU climate, A-, but I think A is fair.