Flandre is amazing on f30, what are you talking about. manipulate equipment her so she's the slowest, I lead with Youmu/Nitori/Eiki/Flandre and they kill everything outside of bosses on the floor before they even get a turn (bar those that outspeed me anyway like chen or that have some phases you have to go through first like mokou or rinnosuke) don't spread lies like that.
with that said, there is no "bad party" there are only unoptimized parties and the ones that have everything in mind you need. I did several testruns with fucked up parties (I have too much freetime :V) all over the place. such as nukers only-party, 4-tank party-party, no buffs-party. Hell, I even once had a party without any healers or massive damage dealers (I had people like okuu, mokou and cirno as damage dealers) and shit like that. all of them beat the maingame without many problems. of course, plus game is a different story, but nobody is doing parties like that. everyone will have a mix of tanks, buffers, healers and nukers/trashcleaners.
now, to DarkAtma's party: my personal opinion is that you don't need a tank outside of special fights (Flandre, Rinnosuke, Okuu, Eiki), but everyone is always like "NEED TWO TANKS :V" and I don't understand why. I agree that meiling is a fantastic character, but if people decide against her, why use a tank at all? I've beaten the winner 14 times now, and all of them were done with Youmu as my damage soaker, with Reimu in second slot. neither of those are actual tanks like Komachi, Meiling or Tenshi. please someone explain to me why you're all over the characters that are tanks before anything else (outside of meiling). My optimal party would have like half nukers to cover every element :V i'd say my ideal party goes something along the lines of
1. Reimu
2. Youmu
3. Nitori
4. Eiki
5. Iku
6. Suwako
7. Minoriko
8. Kaguya
9. Rumia
10. Renko
11. Suika
12. -any powerful fire nuker- I usually choose alice or patchouli. Flandre is really hard to use, but definitely the strongest girl there is.
I like to have coverage. the only reall powerful CLD nuke is kanako's CLD attack, but kanako is so average in everything else, so I like to replace her with any other character. coverage is something you don't need against the winner (powerful non-elemental attacks are the best for him), but certainly while you grind! and you just have too much fire in your team. Flandre, Orin, Yuugi, (okuu and patchouli), and you basically have no coverage outside of it, aside from patchouli's other spells, giga flare and marisa (who is, by the way, completely useless against anything not weak to MYS). I know you chose your team according to how much you like the characters, but a team like that would require more grinding than actually necessary to defeat the final bosses. especially the serpent of chaos is going to be a pain in the ass on every not-fire-weak turn. it's gonna kick your butt badly.think about who feels most useless (or who you like least, really) and replace them with someone who can give you extra coverage or someone with a powerful non-elemental nuke (youmu, nitori, eiki)