Sanae-B got me to Stage 6 on the first time I tried it out, maybe try that or something, I dunno; TH12's pretty hard on its own. If you consider there's actually no beginner's shot type on this one; for each character there exists one shot type that will help against Shou and another one that helps against Murasa. Or you can also simply segregate them as area-shot and the other as focused-shot. Sanae-B just happens to be able to fulfill both of those roles, for some odd reason, not to mention she has the longest invisible time from bomb too.
I use Marisa-A because... well, it's Marisa and is actually the only speed that I can actually make sense out of. I just couldn't 1CC Normal using Marisa-B because Murasa's being a bitch, but then again with Marisa-A I have major problems with Shou for some odd reason.
Also to remind that, unlike the early Touhou, the bombs are actually similar in role to its shot type. E.G. TH07 Marisa-A has focused shot type with a spread-type bomb, and Marisa-B has area shot type and powered bomb, while in TH12 Marisa-A gets both the focused shot type and powered bomb.
I use Marisa-A because... well, it's Marisa and is actually the only speed that I can actually make sense out of. I just couldn't 1CC Normal using Marisa-B because Murasa's being a bitch, but then again with Marisa-A I have major problems with Shou for some odd reason.
Also to remind that, unlike the early Touhou, the bombs are actually similar in role to its shot type. E.G. TH07 Marisa-A has focused shot type with a spread-type bomb, and Marisa-B has area shot type and powered bomb, while in TH12 Marisa-A gets both the focused shot type and powered bomb.