I can destroy plants too, in my weak non-guardian/alien life form body. Also Goku(and most other characters in DBZ) have their powers regardless of what universe they are in. Also in regards to Goku vs Superman it really does depend on which versions are fighting. Goku would stand a fighting chance against almost every version of Superman and would wipe the floor with some of the others. The main version I keep seeing pop up is Superman Prime, in which case yes, Superman does win.