Duck Hunt has some flaws but by far the biggest flaw is how inconsistent his properties are. I'll give some examples off the top of my head.
- The gunman will protect you from all of MegaMan's projectiles... EXCEPT for his sawblade.
- Gunman's bullets can be reflected, but not absorbed.
- The Frisbee will protect us from samus's fully charged B, but not some of her other projectiles