Microwave the butter in a large microwave-safe bowl in short bursts until just melted, then whisk in the hot sauce and garlic powder.
Add the shredded chicken and toss to coat.
For a stovetop option, melt the butter over medium-low heat, turn off the heat, add hot sauce and garlic powder, then transfer to a bowl and mix with the chicken.
In a separate bowl, whisk together Greek yogurt or sour cream, lime juice, olive oil, salt, and pepper.
Add the coleslaw mix and toss to coat evenly.
Stack the tortillas on a microwave-safe plate, cover with a damp paper towel, and microwave until warm, about 30 to 45 seconds.
Wrap in a kitchen towel to keep warm.
Assemble the tacos by adding a layer of coleslaw on each tortilla, followed by buffalo chicken.
Garnish with scallions and crumbled blue cheese.
Serve immediately and enjoy.