Arguably one of the most important party members you can have, Reimu boasts fairly average stats that are greatly aided by her fast leveling speed. This is important, as nearly every stat is important to her. She's the first character with access to PAR and composite-based attacks, and for much of the early game will mow down enemy parties with Fantasy Seal. As the game progresses, however, more enemies will be carrying high defenses in both stats or a resistance to SPI, and her usefulness in random battles will be slowly pushed more towards the PAR effect of Evil Sealing Circle, if at all. In the meantime, her SP pool will continue to grow and grow, and make Reimu stand out even more in boss battles. Great Hakurei Barrier is your best defensive option in the early game, even if it is expensive then. Even as other characters join that can perform defensive buffing, Reimu's Exorcism will shine even brighter, being the strongest party-wide heal spell in the game. As there is no mid-battle revival, avoiding death in the first place is a key aspect of Labyrinth of Touhou, and Reimu will be invaluable to nearly any party as a result.
Gains an extra 70% MAG and 5% T.MND to the formula for every extra 16 SP consumed, however cannot go above 1400% MAG
Useful before a Master Spark
Character Overview and Comments
Marisa is part of your initial party
In the early game, Marisa begins as a fairly standard mage - she's on the frail side, wipes out enemy parties with Asteroid Belt, and... doesn't do much else. As your party roster begins to expand, however, Marisa will gain the SP to begin performing Master Spark, and her role changes dramatically. Master Spark boasts the single highest damage formula in the game, and it only gets better as Marisa's max SP continues to grow. To make the most of it, you want to use her Concentration or other buffing spells from allies to raise her Magic stat high, then fire off a Master Spark, and swap her back out and let her SP recharge until she's ready for another. A great deal of later bosses - especially in the Plus Disk - enter a desperation phase in the final chunk of their HP, at which point they become incredibly dangerous, and Marisa's ability to burn off a huge chunk of a boss' HP in one shot can save your hide. Just be aware that she is limited to MYS element, and anything with a high resistance to it will be neutering Marisa's damage, even with Master Spark.
The first tank to join the party, Remilia boasts some excellent stats, though they are slightly offset by her slow levelling rate and an unusually low starting attack power. Despite that, early on you're going to be having Remilia soaking up damage and giving it back out, and she certainly won't be lacking in those abilities later on either. Her high defensive stats and ability to self-buff make her a good all-around tank without any glaring defensive weaknesses, though there are options which excel in each of those individual qualities later on. As for active battle strategy, Remilia only boasts two spellcards with very obvious applications. Spear the Gungnir's single-target limit does diminish Remilia's usefulness in many random encounters, but does its job well against a single target thanks to her good stats and its low delay. Meanwhile, the powerful Curse of Vlad Tepes is very risky to use at first, but its detriments can be offset at first with a character who can heal those ailments, and later by equipping ailment resistance gear to Remilia.
Sakuya begins the game mostly effective as a wide-range physical attacker, able to sweep aside enemy parties with Soul Sculpture and her decent attack power - while she's got the SP, anyway. Unfortunately, this begins to fall behind other characters in damage output, and her use in random encounters will begin to falter. Once her SP begins to rise higher, though, another use for her begins to shine through as a speed buffer. Her sufficient defensive stats in all areas will help her stay out on the field long enough to throw out a Luna Dial or two, doubling up the party's speed, and thus significantly increasing the amount of turns they get, which can make a huge difference against bosses. Thanks to The World's low delay, she can even max her own speed before beginning Luna Dial use as well. Ultimately, she is set apart not by her ability to buff speed (Other characters later can do this too), but rather by being able to buff several people's speed at once, which no other character can do.
Best choice against High-MND targets and most bosses
Character Overview and Comments
Patchouli is part of your initial party
Blessed - and cursed - with the best and worst values in a large number of stats, Patchouli is the game's purest black mage. Boasting a variety of enemy group-frying spells to take advantage of elemental weaknesses, and a powerful single-target, non-elemental spell that has some great defense piercing for its multiplier, Patchouli is a strong source of magic-based damage for both encounters and bosses, and retains that quality from start to finish. If you're going to use her, be careful - she has some abysmal speed so many enemies will act before her, and her lack of HP and DEF means that almost any physical attack will wipe the floor with her, excluding row-based attacks if she's in the farthest slot. Of course, this doesn't necessarily hold true for some boss fights focused on magic attacks - Patchouli's incredible MND will allow her to be near-invincible in those instances, so take full advantage when you can. Just watch out for her ailment vulnerabilities and defense-piercing attacks if you plan on using her for tanking.