To get one of your sons on the V5 become a Mametchi, give the whole Family excellent care. Play with them to make them happy instead of feeding them snacks. Get their bonding up to 100% before they turn into adults. When they call for training, choose the FIRST option. Not the second or the third, but the FIST.
Also if you keep your bonding to 100% their whole life, get your Mametchi to marry a Chantotchi and you'll get the Pure Mame Family! =D