1) He packed so much personality in a measley 512 polygons
gif via bandicootmaniasite
gif via lareinalela
gif via 90skidsarethebomb
gif via 1hp-1mp
2) Neo Cortex > Dr. Robotnik, just gonna flat out say it.
(personally a fan of Clancy Brown's version)
3) His best friend is also a power-up
via Matt McManis
4) Unlike every other gaming mascot, he never had a cartoon series, but they did produce this test animation:
5) He was there to make sure N64 owners never forgot who was in 2nd place.