The snubber diodes or Zener diodes must be rated at full motor current as that is what will be diverted through them when the motor is switched.
If you need to clip in both directions use Zeners, set the voltage to 12.5V so they only turn on during flyback.
Simple use avalanche rated FETs in your driver circuit and none is required. You can use the 4001 if you like it has the capability of doing the job for you.Good Luck and have fun!Gil
Any diode even a signal diode can be employed as a flyback diode for the small DC motor but it is important to make sure that the diode should be connected in parallel to the motor and reverse biased.