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Which then wouldn't explain why Sakuya, Reimu and Marisa are able to collect the essence of spring along the way which Yuyuko wanted to take back from them (and they were using to power their cherry borders which are like fucking bombs for how broken awesome they were).
I imagine you could explain it away as part of a ritual spell Yuyuko performed that allowed Yuyuko and others to gather the essence of spring, magic is common in Gensokyo and all the main characters can manipulate it in some way or another either through divine power or arcane, but it's just a minor detail in the larger plot device.
In Imperishable Night each team has someone who is able to freeze the night, for some of them it makes sense. Yukari manipulated the border between night and day, Sakuya used her powers on a larger scale and I suppose the other two teams would have to have used some kind of magical ritual as they don't have those kinds of powers.
Also, Eirin is able to replace THE MOON (or at least it's representation in Gensokyo) with magic. So yeah, it really is a fairy tale setting where things follow a odd childish logic, the kind where people think the Earth is flat. Gensokyo as a place is described as a world of phantasms and faith so this kind of thing is probably much easier there.
Either way, I don't see much point in arguing over who's the strongest in the Gensokyo universe, ZUN will trample over anyone's misconceptions any time he feels like writing a new story and everyone has a chance to shine.