Simply calling attention to the technique should be sufficient. For example, "
You have listed a number of arguments, all of which deserve to be addressed. However, let's take one at a time."
A more assertive response might be "
You have made many unsupported claims, all of which have been debunked ad nauseaum." You can continue with "
I would be glad to debunk them all for you here, but this would be outside the scope of this debate." or "
Let's take them one at a time."
Another technique is to simply provide a link to place where someone else responded to the claim. For example:
Person 1: The earth is flat. Pigs fly. Elvis is still alive.
Person 2:
"The earth is flat." - No, it's not:
http://nasa.gov...
"Pigs fly" - No, they don't:
http://pigsdontfly.com...
"Elvis is still alive" - No, he's not:
http://elvisiswormfood.com...
The important part is to project confidence that these claims being made are without merit (if, in fact they are).