We decided to tackle the assembly of a Dynacraft Twilight Twist 16 inch girls bike in a how to video. The bulk of the work is simply tearing all the packaging materials off of them. Assembly itself is really easy and doesn't take more than a few minutes.
For assembly all you really need is 13mm and 15 mm sockets (impact driver to make it easy) and a screw driver to tighten the reflectors. I'd definitely pick up a park tool 3 way socket though, just to have a quick and easy tool to carry with you in case you need to make minor adjustments to the brake.
Twilight Twist 16" bike
Park Tools bike stand
Park Tools 3 way socket