If you mean "advantaged" steps, then here's the answer:
Usually in the Pokewalker, 20 steps gives you 1 Watt. With a Pokemon of a certain type, that changes to 15 steps for 1 Watt. Also, in order to find certain Pokemon or items, you would need to walk a minimum number of steps in order to "unlock" that Pokemon or item. Advantaged-typed Pokemon only need 75% of that number of steps in order to unlock it. See this page for details, look at the first paragraph of the section linked.
