Everybody Hates Hades: Averted. Hades is one of the good guys, if a bit rough on the edges, and even hates most villainous portrayals of him save one. In fact, this trope is the only reason why he hates his job.
Hades: I was fearsome, yes, and I still am even today, but I would never plot against my brothers.
Fake Brit: Marty Friedman as the voice of Draco/L.A. Strong.
Four Is Death: And four Pretty Cures are hired by the Greek god of death himself to protect Persephone.
Playing Against Type: Hades as a fictional character is an In-Universe example; a bunch of movies and TV shows based on Greek mythology seem to like casting him as the villain. In this series, he's one of three characters that play the role of Big Good.
Shout Out: The rearrangements of the names of three of the villains is quite reminiscent of a similar rearrangement of the names of three of the villains (specifically M. Bison, Balrog, and Vega) in Street Fighter.
Unfortunate Name: In the original Japanese version, L.A. Strong/Vlad. It doesn't help that "Vlad" and the comparatively benign "Brad" can be spelled the same way in Japanese.