Talk:Size/@comment-24281553-20180917094037/@comment-36375292-20180917094634

They're immune. If a condition that states something like "You may only cast this card when an opponent calls a size 2 or less monster", then unless you meet the conditions, those cards won't work at all.

It's be the same as calling a size 3, since both sizeless & size 3 monsters DO NOT meet the conditions at all.