In a skillet over medium heat, add olive oil. Once hot, add the shredded chicken, chili powder, cumin, garlic powder, onion powder, salt, and pepper. Stir to combine and heat through, about 5 minutes.
While the chicken is heating, warm the tortillas in a separate skillet over low heat for about 30 seconds on each side or until pliable.
To assemble the tacos, place a generous amount of the seasoned chicken on each tortilla.
Top with shredded lettuce, diced tomatoes, red onion, cilantro, and avocado slices.
Serve with lime wedges on the side for squeezing over the tacos.