Cook and stir ground beef in a skillet over medium high heat until browned and crumbly, 5 to 10 minutes; drain fat. Transfer beef to a slow cooker and sprinkle with onion and taco seasoning mix.
Stir white beans, red kidney beans, white kidney beans, ranch-style beans, pinto beans, black beans, hominy, and tomatoes with green chile peppers into beef mixture.
Cook in the slow cooker set to Low until cooked through and flavors blend, 4 to 5 hours.
