Is there any aqueous solution (or simple method) to remove trace level of sulfur dioxide/nitrogen monoxide and nitrogen dioxide in a gas stream?
Removal of $\ce{SO2, NO2}$ from solution

As mentioned by Maurice, you can remove $\ce{SO2, NO2}$ by bubbling the mixture bubble through NaOH or KOH solution, or washing it through a column with flowing NaOH or KOH solution at countercurrent.

Removal of $\ce{NO}$ from solution

You can bubble the mixture through $\ce{aq.FeSO4}$ solution.
I remember doing this in eudiometry experiments.