Really shoulda considered catcombos with them as well. Literally the worst one could be argued to be near the top because they are in a 3-slot L research combo. One of the 2 best research combos in the game Kimono champs.(Also has the best Unit Himeyuri but thats besides the point)
Monthly Cats mostly are against Red because they are obtainable early on in the game. And Red enemies are the first enemies and most enemies you encounter early on. Courier is not obtainable early on.
new to this channel, but this is probably one of the best battle cats analysis videos, and the best tierlist video i've seen for battle cats. keep up the good work man!