I have a 3 cakes due for Saturday. 2 of them have fonant figures on them. My question is, One is being picked up tomorrow for the party on Saturday. It is a batman cake with Walmart Bettercream on it I have fondnat/gumpaste buildings and such to attach to the cake, will it be ok to attach tonight for tomorrows pick up with Saturdays party. It will be in the frigde in a cardboard box. Also the other one is a gymnastic cake, would it be ok to do this same thing to a cake cake covered in buttercream? TIA!

Fondant figures are not a good thing to put on the refrigerator... Put them just before pick up.
If the fondant is cold, it ill condense air's humidity on the fondant's surface. it will make it turn soft...