u will not duel them cause they are just shop keepers not duelists

u can duel with them or even ask them to be ur partner.
Just clear d game once then u can duel with sadie.
But 4 dorothy u need 2 wait until the festival then choose to duel with dark magician
dorothy

u can duel with them or even ask them to be ur partner.
Just clear d game once then u can duel with sadie.
But 4 dorothy u need 2 wait until the festival then choose to duel with dark magician
dorothy

To duel them, u need to finish all 3 parts atleast once..
then next time you go to the shop, and sadie is selling sandwiches, talk to her, she will
tell you that she has started dueling, you can then request a duel with her.. BEWARE:
Sadie can be very hard to beat.
With Dorothy, you have to wait till the school duel festival,
there when dark magician girl appears and wants to duel with u, Dorothy will speak saying
she wants to duel instead. Choose her and you can duel her. After that, she will be
available to duel against, provided in the shop she is selling the sandwiches at the time
and not cards.
Hope that helps