Choosing Vds value for low-side switch
Vds needs to be at least the supply voltage, as the full voltage will appear across the FET when it is off. Additionally, a DC motor will generate a sizable back EMF when switched off, so a freewheeling diode is necessary. Using a Schottky diode will prevent issues with recovery, other diodes will still have a short, but usually tolerable spike generated, and the FET needs to be capable of withstanding that.