In a large bowl, combine the chicken cubes, buffalo sauce, olive oil, garlic powder, onion powder, salt, and black pepper. Toss until the chicken is well coated. Marinate for at least 30 minutes in the refrigerator for best flavor.
Preheat the grill or a grill pan over medium-high heat. Thread the marinated chicken onto skewers, leaving a little space between each piece.
Grill the skewers for about 10-12 minutes, turning occasionally, until the chicken is cooked through and has nice grill marks. The internal temperature should reach 165°F.
While the chicken is grilling, prepare the salad by combining the mixed greens, cherry tomatoes, cucumber, and red onion in a large bowl.
Once the chicken skewers are done, remove them from the grill and let them rest for a few minutes.
To serve, place a generous portion of the salad on each plate, top with the grilled chicken skewers, sprinkle with blue cheese if using, and drizzle with ranch or blue cheese dressing.