For Jack
After you've fed up your high level Irons you will have:
Air - 34
Water - 30
Cold - 20
Plant - 5
Lightning - 9
Metal - 10
Fire - 56
Earth - 5
You're better off making 5 Panlongs to finish of your earths as it will knock off 5 air and water dragons as well. This will leave you with:
11 Air
15 Water
30 Cold
45 Plant
41 Lightning
40 Metal
182 elements required. To tidy up the numbers 1 Sonic, 15 Seaweeds, 5 Snow and 5 Willow will leave you with:
25 Cold
25 Plant
40 Lightning
40 Metal
Then 25 Lichen and 40 Magnetic will finish it off. So,
40 Magnetic
25 Lichen
15 Seaweeds
5 Snow
5 Willow
1 Sonic
91 dragons will finish off your last 182 elements in the most efficient way.