Lameness.
Reimu/Mima - Mima, bored of just sitting around the shrine and nagging reimu, decided to come along for once. Reimu, lacking someone to attend the shrine, made marisa do the chores, so she's not coming along this time. Eat that, secondary main character.
Shot: Amulet/lazor-missle. Kind of a reimu-marisa team, only with mima.
Bombs: Fantasy heaven (hisoutensokulol), TWILIGHT SPA(AAAAAAAAAAAA)RK(!).
Byakuren/Marisa: oooh, what a slacker. Upon finding out the byakuren was also heading off, marisa abandoned her duties to team up with the messiah, if not only for the fun of teasing her along the way. Regardless, byakuren has made marisa go easy on the youkai as terms for coming along.
Shot: Byakuren - Amulets, but instead of reimu's trademark needles, spread, and homing, she uses wave (sprinkler-like?) patterns and narrow streams. No homing in order to be fair to the youkai. Marisa - pfft. Having to go easy. She's had to abandon her high powered lasers and now uses a spread shot, with her missles going outwards at angles.
Bombs: Byakuren - that pattern spaceship thing from her boss battle pops up and OHMYGODEVERYTHINGAMULET-EDTODEATH...."sorry youkai!" Marisa - As part of going easy, marisa is using the non directional laser instead of her master spark.