Don't even need any special other powers, just a spotter and someone that can handle some math to take load off Yui, plus a few days to practice fire discipline and get things repeatable. Spotter calls a location, probably a street address. Director figures out range, elevation, and bearing, and passes that to Yui. Spotter starts passing video from their cell phone to tighten the loop. Yui fires a small nonlethal beam. Spotter observes, provides a correction. Larger corrections go through the director, who provides Yui with a range-elevation-bearing correction. Fire another small nonlethal beam. By this time they're probably catching it on video, so Yui gut-feels a final correction and fires for effect. Extra powers just make things simpler - for example, Minami as the spotter can probably get ranges and bearings directly out of her power without having to crunch the numbers, or Maiko might be able to provide changes to elevations and bearings using cheap magical illusions to take some load off Yui. The biggest difficulty would be Yui learning what it means to adjust her aim by, say, 45 seconds of arc, which'd probably require a day or two of practice.