
Actually if the dog is overqualified for the class then it can be transfered to Open class only.
If it is a Minor Puppy class and the dog is over age then it can go in the Puppy class, if it is in puppy but overage then it can be transfered into Junior, but otherwise if the dog is ineligible it must go in the Open class.
You will find these rules in the show schedule, Definition of classes, it is before it lists each class, and in that section it tells you what awards count as Chalenge certificates etc.