What should I do for the new inputs added dynamically?
Give them a name, any name
Is there a way to use the plugin without using the name attr?
No
Is there another solution?
It depends on what you are doing with the fields - you clearly don't need a name on them for any other reason than to make jquery validate work, so why don't you just make up a name and call them all that?
correction - need unique names see comments
var i = 0;
$("#add-choice").live("click",function(){
$("#choices").append("<input type='text' name='bob" + i + "' class='required'/><br>");
i = i + 1;
});