Besides sharing a common origin in bats, the similarities between these two cave-dwelling Pokemon run very deep indeed.
Both are speed demons with fairly average offensive power, with Crobat favouring physical attacks while Noivern prefers special moves. In battle they function very similarly, relying on disruption and stall-breaking rather than brute force. They have the exact same BST, HP, Defence, and Special Defence stats and both can have Infiltrator as an ability.
Which do you prefer, the wyvern boombox or the poisonous assassin?