In a small bowl, mix together cream cheese, pepper jack cheese, goat cheese, garlic, lime zest, oil, chili powder, and red pepper flakes until blended. Stir in onion and cilantro.
Cover bowl with plastic wrap, and refrigerate for 1 hour, or until firm.
Line a baking sheet with waxed paper. With a small melon baller, scoop out a ball of avocado, sprinkle with lime juice, shape 1.5 tsp of cheese mixture around it, then roll in pumpkin seeds. Place on a waxed paper-lined baking sheet.
Cover baking sheet with plastic wrap and refrigerate. Immediately before serving, insert a pretzel stick into each ball, and arrange on serving tray.