Note - Multiprocessing.py doesn't work in IDLE, you have to use software like intellij or something.

def funct(a, b):
   #run .bat file with params (a,b)

if __name__ == "__main__":
    # run as many cores as in the range
    processes = []
    for _ in range(4):
        p = multiprocessing.Process(target=funct, args=[2, "hello"])
        p.start()
        processes.append(p)
    for process in processes:
        process.join()