yes it does. the part people get wrong about doublign season is it does not double the loyalty gained by using + abilities, but it DOES make walkers enter with double counters
306.5b A planeswalker is treated as if its text box included, "This permanent enters the battlefield with a number of loyalty counters on it equal to its printed loyalty number." This ability creates a replacement effect. And Doubling Season's Oracle rulings: 10/1/2005: Doubling Season affects cards that "enter the battlefield with" a certain number of counters. Triskelion, for example, would enter the battlefield with six +1/+1 counters on it rather than three.
