For easy clean up, use a slow cooker liner.
Cook ground beef in a large skillet over medium-high heat until browned, about 7 minutes. Season with taco seasoning.
Transfer beef mixture to the slow cooker. Add enchilada sauce, beans, green chilies, and onion, and stir to combine.
Cover and cook on Low for 3 to 4 hours.
Stir in 1/2 of the tortilla wedges and 1/2 of shredded cheese. Top with remaining tortilla wedges and cheese. Cover and cook on High until cheese is melted, about 30 minutes more.
Garnish with cilantro, pico de gallo, and sour cream.