In Chicago a hot dog has mustard, onions and relish. Sport peppers are a likely possibility. A classy place may have a pickle and a tomato.
We would never put catchup on a hot dog. If any one asks for it they are either a tourist or not raised very well. Asking for catchup goes a long way to explain the high homicide rate here.
The best hotdogs are made by Vienna.
What goes on a hot dog where you live?