Text (UH): The attacking or blocking creature with the lowest collector number has first strike. If two or more creatures are tied, they all have first strike.
Token creatures do not have collector's numbers. And some cards may be misprinted without a number and thereby have no number as well. [Unhinged FAQ 2004/11/15]
If neither creature has a number, no creature gets a bonus. [Unhinged FAQ 2004/11/15]
All tournament formats have banned cards from Unhinged.