This move effect may be in need of research. Reason:If both Pokémon are immune, does it still try to hit both Pokémon? How does it interact with Ally Switch when targeting an ally? Does substitute or Ice Face cause Dragon Darts to be redirected away from the Pokémon? Is it affected by Wide Guard? Does Follow Me still redirect the attack if the user would take no damage? If the user has Mold Breaker, will Dragon Darts take that into account when determining its targets? How does it targeting work if a raid max battle uses it? You can discuss this on the talk page.
If targeting an opponent when there are multiple opponents, Dragon Darts' first strike targets the original target and its second strike targets the other opponent. If either the original target or its ally would take no damage from Dragon Darts, both strikes are directed at the other Pokémon instead. If Dragon Darts targets an ally, both hits will hit that ally.
The following reasons for taking no damage from Dragon Darts will cause it to target the other Pokémon:
If Dragon Darts would miss due to the user's accuracy or the target's evasion
If one of Dragon Darts' strikes is redirected in order to avert a miss due to accuracy and evasion, this will activate the user's Blunder Policy (even if both strikes successfully hit the other Pokémon).