Heracross is the quintessential Pokemon. He is the best representation of a Pokemon.

Pokemon was based on Satoshi Taijiri's love of bug collecting. He said he imagined bugs crawling across the link cable when he envisioned trading. Beetles are the most prized bug in Japanese bug collecting, specifically Japanese rhinoceros beetles, or kabutomushi, on which Heracross is based.
Beetles are also pitted against each other in battle, and even bred by children and hobbyists. These, along with collecting, are the core mechanics of Pokemon. Beetles also fight in the wild, and consistently win in Japanese bug fighting competitions, making them the quintessential fighting bugs. Heracross's type and concept reflects this. He is a fighting beetle.
Heracross's design is simple but memorable, imposing but also endearing, with lots of attention to detail and brimming with personality. He represents the ideal of Pokemon design, the way a Pokemon should look, and what sets it apart from other fictional creatures.
Even his mega is what megas should aspire to be: an alternate form, both in concept and playstyle, rather than a strict upgrade (when the Pokemon is already viable). A different take on the same concept. Heracross's mega represents a whole other facet of Japanese popular culture, namely mecha, which draws inspiration from samurai culture, which in turn drew inspiration from the kabutomushi. The design comes full circle. It explores the concept from a different perspective, elevating it to a higher level while preserving its integrity, and without overshadowing the original. This is what a mega form should do.

Heracross is truly the model Pokemon.