WMG / Futari wa Pretty Cure

Futari wa Pretty Cure is set in the same universe as Negima! Magister Negi Magi

Evidence: Nagisa and Honoka appearing at the Mahora Festival in the fourth panel of a page.How did they end there? Well, after the Dark King attacked Earth directly the mages finally tracked the Pretty Cures, and to keep The Masquerade offered them a scholarship and training in Mahora. It would also explain how they became able to one-shot a Zakenna in the All Stars movies: the training paid off.

• The panel shows Cure Black with her midriff outfit which she wore in the first season. It would have happened during the first season.
• Their trainer is Evangeline, who forced her to use that outfit.

Futari wa Pretty Cure is indirectly based on events in the past of Futari wa Pretty Cure Splash★Star.

We know from Saki's English quiz that some TV show called Pretty Cure exists in the Splash Star universe. According to an early episode, there's been at least one Pretty Cure in the Splash Star universe prior to Saki and Mai. It's not unreasonable that the two might be connected.

In the distant past, Dark Fall made an attempt to capture the seven fountains. A pair of women named Nagisa and Honoka, aided by the spirits Mepple and Mipple, fought them off and won, but didn't quite manage to wipe out the bad guys. (Possibly, they never realized Goyan was the real Big Bad.) Their story was known in part by the Muggles and, through repetition, it lost details (such as Uzainas being produced from different things depending on who creates them), and some things got mixed up.

Fast forward to the modern day, where some Toei exec decides that a modernized version of the old Pretty Cure "myth" would make a great anime. Nagisa and Honoka were recast as schoolgirls, with the added "complete opposites" angle, and new names were made up for everything whose real name was forgotten. The Hikari angle was probably invented as an excuse to extend the show for another year as Max Heart. (Alternatively, perhaps instead of the Queen being restored to her original form, the real Hikari regained the Queen's power and memories in her current body, becoming the Filia we know.)

Since both the legend and the TV show are well known, Flappy assumes Saki and Mai will instantly understand how this Pretty Cure thing works. This is why he's so uninformative about it at first and irritated when they need things explained to them.

• The fanfic version, Futari wa Hearty Pure, is confirmed to be based on such a legend, only this time with the two women being renamed Nadeshi and Hanako like in the series, in an early episode of Pretty Cure Heavy Metal.

Cure Black is a Kamen Rider disguised as a magical girl.

Cure Black's voice actress Yoko Honna had a recurring role in Kamen Rider BLACK.

• Is Atomic Betty is also a Kamen Rider? (Yoko Honna voiced Atomic Betty in Japan.)
• In Heartcatch, Tsubomi's mother's maiden name was Kaoruko Godai. Within a couple of days of that fact being revealed, this piece of fanart◊ appeared.

Cure Black is a magical Silk Spectre II.

Same reason as above, only this time Honna was also the seiyuu for Silk Spectre II in the Japanese dub of Watchmen.

Nagisa and Honoka became Heterosexual Life-Partners after the end of Max Heart

Their powers depends from their feelings for each other. Now, in the series Zakenna always gave them at least a decent fight, but in the first All Stars movie they one-shot two Zakennas in a row. My guess is that their powers have been brought up to eleven with their feelings...

Ryouta actually knows that Nagisa is Precure

He knows that she's strong,as seen in episode 26 of Max Heart,so why wouldn't he know that she is Precure?

Sanae used to be a Cure called Cure Hope

A certain fanfic thinks so and it goes well with the fact that Tsubomi's grandmother used to be a cure called Cure Flower.

Theory regarding why Hikari/Shiny Luminous is still in her human form

If you really think about it, Hikari being the life of the Queen of Light, she should no longer be present after the Queen is reformed. She even bid farewell to the Cures in the final battle. Yet she is still out there in her human form in the epilogue.

Hikari is really a weakened form of the Queen. In the final battle the darkness is significantly weakened, however since the modus operandi of the Queen is maintaining the balance of the universe instead of obtaining supremacy over the other, her full power is no longer needed. She thus weakened herself by splitting part of her own power into another entity, in this case reforming Hikari.

Nagisa and Honoka aren't the first Cure Black and Cure White to defend the Garden of Light.

There was a time in the past, possibly even before Mipple and Mepple were born, when there was another pair of Cures named Cure Black and Cure White, and they had a different pair of fairy partners. Their names were Keiko and Yoshiko, and this is why the Elder keeps thinking those are Nagisa and Honoka's names.

Nagisa and Honoka became an Official Couple some time after Max Heart's ending

The merchandise that Toei Animation has brought out of them in recent years is a bit suspicious (they literally released a figure of them two together dressed as brides), as in HU Gtto! PreCure ♥ Futari wa PreCure: All-Stars Memories.