You can REALLY see the influence of Sailor Moon and of Sailor Stars. Especially in the plot of having a rivalry of "other world" Senshi/Cure and Earth Senshi/Cures as well as the fact we having someone singing to summon a princess, and that princess is young/a baby (with heart odongo hairstyles too!). Also the enemies are a human looking group (Sailor Moon kept this for all seasons) who bicker amongst themselves in their own bar (SuperS reference?). The enemies are all people with corrupt hearts (star seeds/dream mirrors/etc.) which are then purified back to being human.
-Cure Diamond′s pose is similar to Sailor Venus′ pose.
-Regina looks like Minako Aino/Sailor Venus.
-Ai is similar to Chibi Chibi.
-Cure Sword and Sailors Starlights came from another dimension and became idols to search for a princess.
Not exactly an idol anime (it's in the magical girl genre), but one of the girls is an idol and there are several episodes focusing on that! Also, the endings have the Cures on stage dancing and singing. Like Pri Para, it focuses on friendship and the importance of teamwork and trust!
Dokidoki! Precure and PriPara are both really good! But Dokidoki! Precure isn't much about idols and singing... But the main characters all all like, "I want to make others smile!" and stuff like that. Dokidoki! Precure is mainly trying to cure selfish people or people who got turned into selfishes. PriPara is just idols, idols, and even more idols xD If you PriPara, you should definitely watch Dokidoki! Precure.
Doki Doki Precure and Nyanko Days are both very innocent and cute anime with sweet and kind characters. Both shows are very bright and happy with cute animal companions. While Precure focuses more on making the world a better place, Nyanko likes to focus on friendships, especially those between people and pets. If you're looking for something to brighten your day, both of these shows will let you see the good in life.
If you really like Doki Doki, you might just love Black Butler! Doki Doki Precure often makes references to Black Butler. You can additionally get easily hooked to the two endings they both have. Not to mention, they both have butlers with the same name. Don't forget the epic battle scenes! Just switch the gender roles, Doki Doki is like a feminine version of Black Butler and vice versa.
There are in my opinion 2 of the best series of the Precure Franchise. Both series target a young shojo public but the plot can even make an older public watch it.
Also both have the same characters designer. Coincidence ? I think not.