No power in Gensokyo is limited because we of the "real world" believe in limits to bloody well everything. While we're on the reversal subject, we also believe just about anything will give us cancer, so no noticeable causes of cancer in Gensokyo either... Hey, let's all move to Gensokyo! :V
Really, in a fight between just about any character in Touhou, the danmaku rules would come into play, and then the fight would play out by who dodges the best, and end just as any Touhou game would, with tea parties and proof of one character's dodging/danmaku-spewing skills. If they fought with their real powers, then say goodbye to Gensokyo unless one of the higher-ups with a lot of power notices and cares.