Hi Pamela,
It does appear that the Pixar Pals Countdown to Fun! parade at Disney's Hollywood Studios has ended. I have searched for this parade, and it no longer is listed on the
entertainment schedule for Disney's Hollywood Studios.
But don't worry, there are other places to visit Woody and Buzz Lightyear! I see that today you could meet Buzz Lightyear and Woody at Pixar Place at Disney's Hollywood Studios. Also today, you could meet Woody and Jessie in the Splash Mountain Exit Courtyard at Magic Kingdom Park, and you could meet Buzz Lightyear in Tomorrowland in Magic Kingdom.
The ways that I find out what characters will be appearing when and where are first to us the My Disney Experience app on my mobile phone. You can also find this list of character meet and greets listed by park on the Walt Disney World website. Here is
today's entertainment schedule for Magic Kingdom Park including character meet and greets. Also, when you arrive at the theme parks, be sure to pick up a Times Guide along with your theme park map for the day. The Times Guide lists character greeting times.
It does seem like your boys will be able to meet Woody and Buzz Lightyear. Have a great trip, Pamela, and please do not hesitate to ask if you have any further questions!