Aikatsu on Parade is the MCU of the Aiaktsu world. It takes characters from ALL seasons of Aikatsu and puts them together, whether they were in the same universe or not, with an original main character to steer the story. While this sounds super fun, and don't get me wrong, it was, overall this show was a bit of a mess and a few major flaws made it unlikeable.
Animation was fine, best in the franchise so far. Both the regular animation and especially the CG concert scenes have come a long way over the years.
This show has all kinds of music from all the other shows in the franchise, which is great for Aikatsu fans. Even the closings are all re-used from past seasons, which is nostalgic. I've personally always thought most of the music was catchy.
The basic premise is an Aikatsu engineer somehow creates a dimension-traveling Aiaktsu card, that when swipped, allows the holder to open a gate to different dimensions (specifically, idol schools). The engineer's little sister, and our newbie idol protagonist, Raki, is unknowingly given the card. She quickly befriends Aikatsu Friends protagonists Aine and Mio as she enrolls in their school, and they end up traveling to another idol school when the card is swipped and a magic gate opens up. They then use then use the gates to travel to different idol schools from past seasons. Eventually, the show scraps the gates and vaguely says 'btw, now all the idol schools/worlds are connected' without any explanation of how slamming a bunch of universes together even works.
The rest of the show can be summerized as 'cross-over the show', as there is no overall plot or goal, but each episode (occassionally two or three part) is a self contained activity where idols from different seasons do an idol activity together. These activities are very similar to ones that repeat every time the franchise is rebooted, except most training/learning episodes are removed.
The super vagueness of the universes crossing over is a HUGE plot hole. Often with kids shows you can ignore some parts that don't totally make sense (ex: downloading dresses off of cards to wear), but since the entire show literally revolves around dimension jumping/combining its very distracting that no explanation is ever given on how it woks. Raki's sister makes little cameos every once is a while but never mentions how or why she decided to mess with alternate dimensions.
The other problem with the 'story' and setting is it follows the character Raki, I'll explain more below my specific issues with her, but it just doesn't make sense to use a brand new idol as a catalyst for the entire show about pre-existing super famous idols. That would be like me staring in a movie with (and upstaging) Beyonce, Gaga, and Madonna. WHY. It would make more sense to just use the protagonists of Aikatsu Friends, or of any other season, instead.
This show has all main and secondary idols from ALL the previous seaons in the franchise, which is FUN for an Aikatsu fan. Its great to see them meet and interact, even if its shallow conversations. Of course watching them preform is the most fun. There are also a large amount of cameos of minor characters too, which creates a 'spot-it' game while watching. The downside to such a huge cast, especially since they're almost all pre-existing, is there is zero character development or progress. It gives the show almost of a 'non-canon movie' feel since they acomplish nothing note-worthy. The show's greatest strength is also part of its downfall.
The BIGGEST problem in this show is the protagonist Raki Kiseki. She is a 'Mary Sue' through and through. On her first day at idol school, before her first class, she befriends Mio and Aine, two of the most popular people in all of Japan. Then, instead of actually going to idol school/classes, she gets to preform with them (and their other famous friends) and naturally be able to sing/dance well enough to get tons of praise. Not once in the entire series is she shown to actually attend the idol school, not even a single class scene. Almost every super popular idol she meets immediately considers her a friend and a competent idol, which is just annoying and frustrating. She isn't even portrayed as one of those confident 'prodigy' type characters, but only as a 'tee hee, aren't I so lucky?' type when the most famous people in Japan bend over backwards to help her out with random stuff. Its so irritating. It would have been SO much better if she was like a producer in training or mentioned to have done years of training before the series began. It really feels like a bad self-insertion fan-fiction.
I think, even with the huge flaws, I was able to get some enjoyment out of the series because I'm a fan of Aikatsu, and the cross-overs were fun. However, Raki Kiseki and her sister's dimension-crossing nonsense just felt like a bad self-insertion fan-ficton and it was distracting and maddening. I would only recommend this to large Aikatsu fans (the show assumes you already know who the characters are), and even then, I think its skippable, and possibly the worst Aikatsu show to date. It just has huge non-canon feels. I'm curious to see where the franchise heads after this.