Darkest Day

The Darkest Day (暗黒の日 Ankoku no Hi) is the second battle against Black Hole, which united the first 19 Precure teams.

Beginnings
In the past after his very first defeat whilst as the Shadow Lord, Black Hole faced off against the Precure All-Stars when he had re-obtained seven of his aspects and was defeated due to his lack of power. He soon went into hiding, biding his time as the other twelve pieces of himself are sent back to him year after year, until he was once more at full strength. Once that happened, he launched another attack on the Earth in the hopes of once more devouring the Prism Flower.

But despite their overwhelming power, Black Hole was once more opposed by the now ninteen Precure teams who united as one to defeat him once and for all. Because of the severity of the situation, even former villains like the Kiryuu sisters and powerful allies like the Kyoryugers joined the fight against Black Hole

Early battles
Just days after Kanna had returned to Dino World alongside the Dragon King, the world was cast into darkness while hundreds of revived monsters fought against opposition, he soon called on the powers of the various main villains they had defeated in the past.

19 Precures Assembled
With Black Hole as the latest force to threaten Earth, the 19th and most recent Precure team, the Dino Spirits Precure, went to oppose them, having already fought an aspect of him early on during their tenure. However, it was soon apparent that the Zangyack would not be defeated as easily as them. All 19 Precure teams teams were needed to face them and as such, Misumi Nagisa (Cure Black) and Yukishiro Honoka (Cure White), the original duo of Precure, already assembled the first 18 Precure teams, with Sakagami Ayumi fighting by their side.

The battle was soon waged all around Japan, with some of the International Cures teaming up with some of the past Cures' allies in order to fight against the revived monsters. During one battle in Yokohama, the home of Ayumi, Kyuseishu Kotaro and Sakebu Hinata were helping several civilians get out of a crumbling building with the help of Cure Echo. However after they were giving a headcount of the people in the building, they soon heard the fearful cries of Hinata's daughter Mio from within the building. This forced the veteran of the two to run into the building in order to save her.

Sadly while she succeeded, a nearby gas tank exploded and caused a large pile of rubble to fall onto the two, pinning Hinata down. When Cure Echo tried to save both of them, Hinata pleaded with her to only save Mio instead since she knew that even if she got out, she would not have that much time left alive anyways. Resigning to her fate, the police woman allowed Cure Echo to get a crying Mio out of the building whilst the rubble and fire took her life.

Final Battle
The 19 Precure teams formed an army to face off against Black Hole who had regained his corporal form, with Nagisa and Honoka leading the charge. The Cures, almost 126 in total, converged and toppled the revived generals and their soldiers. During the battle, the Precure teams used their various powers and abilities, and teamed up with their similarly motivated allies to take the advantage over the Black Hole Army, whose combat styles were just as diverse.

Although the Precure put up a valiant fight, they were overwhelmed by the Black Hole Army. Mipple was the first to notice their approach, soon followed by the other fairy allies. Cure Black gave the order for all of the groups to combine their powers into one attack. Mipple and Mepple decided, along with the fairies to infuse their power as well. The resulting blast wiped out the entire army, thus ending the Darkest Day.

Aftermath
On the former battlefield, Kodai Kota woke up, confused as to what had happened. Her team mates soon woke up afterwards as Katsuki Rentaro noted that they were obviously still alive. When Torago Mitsuki asked if they had beaten Black Hole, Shirayuki Hime (Cure Princess), with Kurumi Erika (Cure Marine) by her side, verbally confirmed that their fleet was destroyed, while Erika merely nodded. Tsubasa Yumi ascertained that it was all over as Shōsha Keiko helped her sister Hinata. Keiko said that although it was over, they could never become Precure again, with the Prism Flower being destroyed once more. However Erika clarified that it wasn't fully decimated, but it was merely split apart into twenty different pieces.

Kyoryusei Kanna soon noticed that her Kyoryupon was now blank, confirming that they were powerless. Everyone was understandably feeling dismal, apart from Aino Megumi, who said that, despite the sacrifice, it was for the best as they protected the planet, raising everyone's hopes. The 19 Precure teams proceeded to go their separate ways and carry on with their lives, without their powers. Although they were now powerless, the people of Earth still respected and admired their heroes, who were regarded as legendary warriors.

Precure All-Stars
The participants were all Precure who existed at the time, not counting the International Cures or the Kyoryugers, since the latter was the 37th Super Sentai.
 * Misumi Nagisa / Cure Black
 * Yukishiro Honoka / Cure White
 * Kujou Hikari / Shiny Luminous
 * Hyuuga Saki / Cure Bloom / Cure Bright
 * Mishou Mai / Cure Egret / Cure Windy
 * Yumehara Nozomi / Cure Dream
 * Natsuki Rin / Cure Rouge
 * Kasugano Urara / Cure Lemonade
 * Akimoto Komachi / Cure Mint
 * Minazuki Karen / Cure Aqua
 * Milk / Mimino Kurumi / Milky Rose
 * Momozono Love / Cure Peach
 * Aono Miki / Cure Berry
 * Yamabuki Inori / Cure Pine
 * Higashi Setsuna / Cure Passion
 * Hanasaki Tsubomi / Cure Blossom
 * Kurumi Erika / Cure Marine
 * Myoudouin Itsuki / Cure Sunshine
 * Tsukikage Yuri / Cure Moonlight
 * Hojo Hibiki / Cure Melody
 * Minamino Kanade / Cure Rhythm
 * Kurokawa Ellen / Cure Beat
 * Shirabe Ako / Cure Muse
 * Hoshizora Miyuki / Cure Happy
 * Hino Akane / Cure Sunny
 * Kise Yayoi / Cure Peace
 * Midorikawa Nao / Cure March
 * Aoki Reika / Cure Beauty
 * Aida Mana / Cure Heart
 * Hishikawa Rikka / Cure Diamond
 * Yotsuba Alice / Cure Rosetta
 * Kenzaki Makoto / Cure Sword
 * Madoka Aguri / Cure Ace
 * Aino Megumi / Cure Lovely
 * Shirayuki Hime / Cure Princess
 * Omori Yuko / Cure Honey
 * Hikawa Iona / Cure Fortune
 * Haruno Haruka / Cure Flora
 * Kaido Minami / Cure Mermaid
 * Amanogawa Kirara / Cure Twinkle
 * Akagi Towa / Cure Scarlet
 * Asahina Mirai / Cure Miracle
 * Izayoi Riko / Cure Magical
 * Hanami Kotoha / Cure Felice
 * Usami Ichika / Cure Whip
 * Arisugawa Himari / Cure Custard
 * Tategami Aoi / Cure Gelato
 * Kotozume Yukari / Cure Macaron
 * Kenjou Akira / Cure Chocolat
 * Kirahoshi Ciel / Cure Parfait
 * Nono Hana / Cure Yell
 * Yakushiji Saaya / Cure Ange
 * Kagayaki Homare / Cure Étoile
 * Aisaki Emiru / Cure Macherie
 * Ruru Amour / Cure Amour
 * Hoshina Hikaru / Cure Star
 * Hagoromo Lala / Cure Milky
 * Amamiya Elena / Cure Soleil
 * Kaguya Madoka / Cure Selene
 * Yuni / Cure Cosmo
 * Hanadera Nodoka / Cure Grace
 * Sawaizumi Chiyu / Cure Fontaine
 * Hiramitsu Hinata / Cure Sparkle


 * Saiba Sasami / Cure Byte
 * Chishiki Tomiko / Cure Data
 * Keikai Masaki / Cure Chip
 * Ebu Sumire / Cure Web


 * Shōsha Keiko / Cure Pitch


 * Shōsha Hinata / Cure Goal


 * Kettei Natsumi / Cure Allez


 * Zenbu Asami / Cure Par


 * Erin Hartman / Cure KO
 * Kodai Kota / Cure Claw
 * Tsubasa Yumi / Cure Wing
 * Torago Mitsuki / Cure Jaw
 * Kyoryusei Kanna / Cure Horn
 * Katsuki Rentaro / Cure Gnaw

Trivia

 * This battle is reminiscent of the Great Legend War from Kaizoku Sentai Gokaiger