The Mozart also has a mostly intact solo, doubled at all times with other parts that share the action, for continuity of the rather long melodic lines. This is labeled Flute 1S, designed for one or two players. Alternatively, one flute and one piccolo could share it. The piccolo part was notated one octave down, and is otherwise not necessary. The Alto Flute part is divided into Alto 1 and Alto 2 to cover middle lower harmony. In the absence of two Alto players, un-transposed versions are labelled Flute 4 and Flute 5, with a measure or two bumped up where un-playable by a C Flute. The Bass part is also divided into Bass 1 and Bass 2 to cover harmony. The Contrabass part can be played by a Bass, remaining as much as possible in the first octave. This part is more necessary than Bass 2, which frequently doubles Bass 1. There were tonic “drones” in the orchestral score for folks who don’t need air. They are staggered for breathing purposes between parts here.
Most YouTube performances were at a metronome setting of a quarter note to about 46, to let the clarinet soloist wail soulfully. I suggest 56 for flute ensembles, with which I strongly suspect you’ll be a lot happier!
The Beethoven Adagio is a bit more straightforward. It has a piccolo part and four C- flute parts, and Alto, Bass, and Contra/Bass 2. Again an un-transposed Alto part is in the set as Flute 5 if more heft in the mid-lower range is desired and enough Alto flutes are not available. Only a couple of notes are bumped up to accommodate C flutes. A non-draggy tempo of about 65 per quarter note is what I suggest. The original key of B(!) was transposed to C.