Can anyone help - my son started playing Yu-gi-oh recently and has some Crystal Beast type cards. He sends them to the spell card zone and treats them as continuous spell cards, then states that he cannot be attacked directly when he has no monsters in monster card zones. Is this right or are they no longer counted as monsters that have to be destroyed before attacking life points directly?

His opponent can attack him directily if he has no monsters in his monster zones, while a crystal beast is in the spell/trap zone it is not considered a monster, it is a continous spell card.

yea he has it all wrong if he gets ancient city ruins on the field he can start using the effects on that card that will allow him to take half damage on an attack but he cant just not get attacked or they would be banned