I saw top player's run. He used Blue eyes ultimate dragon. but rule written that 'Any unobtainable cards (Gate Guardian, Perfectly Ultimate Great Moth, Blue Eyes Ultimate Dragon, etc.) are forbidden. Cards that cost 999,999 starchips, and otherwise cannot be obtained, are also forbidden.' What should I believe? rule or any runner. Or I mistake some interpretation?

They are obtainable in the Japanese version and so are allowed if you are playing the Japanese version, but that wording is very poor I agree. It's saying you're not allowed to use them if playing the English version.