Sorry for double post.
I finally beat every challenge currently in the game.
I can pull off 185k without risk on a 3 girl team: Yukiho, Azusa and Miki with a total of 14 memory appeals using Cosmos, Kosmos. With risk free i mean without relying on Azusa's burst. I reach this score by memory 3 times, burst with Yukiho immediately, memory 3 times, burst with Miki and Yukiho, memory 3 times, burst with Miki and Yukiho, memory 3 times and burst with Miki alone. Actually 13 memory appeals are enough for this and results in a score of about 182k by using only 2 memory appeals before the last burst.
If i gamble a bit i can reach 195k by bursting with all 3 idols at the first burst, but for this to work out in the end i need Azusa to give me back one more memory appeal than she uses over the course of the song so i can use 3 memory appeals before the 4th burst.
Of course, with this score (the risk free one) S1 auditions, lives and festivals are no issue.
And i got 245k to beat the S3 quintet live using M@sterpiece with Hibiki, Makoto, Yayoi (bursting) and Yukiho and Azusa (for their memory appeals) with a total of 19 memory appeals. To be able to pull off 4 bursts on M@sterpiece and do 3 trio bursts (the last one is a solo burst from Hibiki) you need to use 4 memory appeals to fill the voltage bar once a fast as possible, preferably the first time which means you need 19 memory appeals.
My current record for an All Star Live is 610k, and especially the vocal team has a lot of extra scoring potential, but i'd need at least 3, probably 4, more memory appeals since i can only burst 3 times with them atm.
All my idols are lvl 40 now.
I hope they add some more challenges with the upcoming catalogs, since i guess they will increase the max level and max idol rank as well.