Create a Python function that takes two lists and returns a list of all elements in common between them.
list1 = [1, 2, 3, 4, 5]
list2 = [2, 4, 6, 8]
def find_common_elements(list1, list2):
  common_elements = []
  for i in list1: 
    if i in list2: 
        common_elements.append(i) 
  return common_elements