Haha! Wow, nice guesses! You got most of them right, I think! Here's the answers:
0. Ruddy Duck
1. Black-bellied Whistling Duck
2. White-backed duck
3. Freckled Duck
4. Common Shelduck
5. Muscovy Duck
6. Wood Duck
7. Comb Duck
8. Torrent Duck
9. Ringed Teal
10. Maned Duck
11. Flying Steamer Duck
12. Blue Duck
13. Northern Pintail
14. Tufted Duck
15. Mallard
16. Baikal Teal
17. Common Pochard
18. King Eider
19. Harlequin Duck
20. Surf Scoter
21. Long-tailed Duck
22. Smew
23. Common Merganser
24. Barrow's Goldeneye
Hehe! Thanks! And don't feel bad - some of them are REALLY obscure/not native to the northern hemisphere!