You can actually get away with a dash attack into an uptilt right on someone's shield much of the time. I'm not sure on the hitboxes on her uptilt but it seems to cover her entire character and has at least two attacks to it. This makes it likely to poke someone through their shield, and there is, of course, no delay between the dash attack and the uptilt.
But I know what you mean. Her dash attack approach is very good, but you need more to not be predictable. Short hop jump spacing for her over-B, try camping out someone elses approach with neutral B, or faking out of an attack by moving up so much distance, then forward rolling past an attack, because her forward roll is extremely high quality. Samus can also do double aerial short hops, but her short hop is still fast because she attacks quickly and jumps/falls quickly. Short hop into uair and then into another uair, bair, or fair work. Umm... you can also dash into an over-B, or a grab. Then lastly you still have the RAR down-B, which when used sparingly tends to surprise people.
I don't think Zamus has any one dominant method of approach. Each in it's own way can be countered or whatever. However, Zamus is fast, and almost all of this stuff works at different ranges and some of those ranges being considerable, like anything that uses an over-B, so by using a variety she can really mindgame her way in past just about anything.