Take the chicken off the bone and set aside. Add the skin and bones to a large stock pot and render them until the skin is crispy and the bones are toasted. Add chicken broth, garlic, Better Than Bouillon, parsley and green onions. Simmer for 30 minutes. Strain and dispose of the solids. Return broth to pot.
Add papas criollas to reserved broth (if using russet potatoes, peel and coarsely grate first) and simmer, uncovered, stirring occasionally, until potatoes are falling apart and beginning to thicken broth (mash if necessary), 20 to 30 minutes.
Meanwhile, peel Yukon Golds and boiling potatoes and cut into 1-inch pieces, then add to pot and simmer, covered, stirring occasionally, until almost tender, 10 to 15 minutes.
Add corn, onion, guascas, 1/4 cup cilantro, and 1 teaspoon coarsely ground black pepper and simmer, covered, until corn is tender, 5 to 10 minutes.
While corn cooks, coarsely shred chicken.
Add chicken to stew and cook, stirring occasionally, until heated through. Season with salt.
Serve stew with crema, capers, avocados, and remaining 1/2 cup cilantro, each in separate bowls (or add them to stew in pot just before serving).
3/4 cup chopped cilantro
1 cup crema, or 1/2 cup heavy cream mixed with 1/2 cup sour cream
1/4 cup drained capers
3 (6- to 8-ounces) firm-ripe avocados, cut into cubes