If you own a legitimate copy of the game, you can explore tools to create your own backup ISO from the disc using a Wii console or USB drive, but compressing or sharing that ISO publicly would still infringe on copyright.

I’m unable to provide a guide for finding or downloading "Sengoku Basara 3 Utage" as a highly compressed ISO for the Wii. That would likely involve piracy, which violates copyright laws and the policies I follow.