I don't think anything about Idoling is common knowledge in the mainstream, basically only the fans are in the know so to speak.
I really think this show did help showcase Idoling quite a bit though, they really know how to seize the moment with all the training they got from Bakarhythm for sure. While Momoko did get her own share of spotlight as an individual, the rest of the Berryz were totally lost in the shuffle. Smileage kids are just not very savvy in that area and it shows. Passpo and SuperGirls have no personality to speak of.
As for the slender Serina winning, it's clearly fixed, when you see the match vs. Aichan, you could tell that Aichan had a lot of momentum going by pushing Serina back at the beginning but then she just stopped pushing and let Serina to hang around and made it appear as if Aichan lost her balance at the end, yeah right, as if Serina has such strength and body mass to overcome that. What I really hate about these type of shows is that it's scripted, and they always let the most popular group win to emphasize the miracle factor, and drill the false belief of AKB always wins because they are special theme into the audience, yuck. I wasn't born yesterday and I sure ain't buying it.
Idoling sumo is for real though without fixing, that's why I love Idoling.
Mecheike won't do an Idoling special the way things are right now, Mechaike is an golden-hour show with top-tier popularity, Idoling alone just isn't big enough for prime time.
I think Amimi is very strong outside the comfort zone, but there are some members who clearly shy away when they are outside the comfort zone, namely Asahi and Yazawa, these two really need to step up to the plate because I know they have the stuff.
On second thought, I think it's too late for Yazawa though, she has become too self-aware and doesn't want to act goofy in a prime-time stage it seems, possibly to prolong her career in acting as an actress or something. 4th gen. members were invisible, were they even there? Well they are still amateurs in the variety arena but for gods sake they have to start showing something to indicate a hint that they belong in Idoling. I'm just not very thrilled with 4th gen. no matter how I look at things, at the least they should start improving in singing, but still nobody is showing any signs of having the diva talent either.
Yeah, it's time for 5th gen. audition, and discover a new singing sensation to continue the legacy of Idoling's divine vocal lineage.