The Most Durable Pokemon Types
Python 2, 784 bytes

i=['Normal','222222422222202222'],['Fire','214211224221422211'],['Water','211441222222222212'],['Electric','222122224122222212'],['Grass','241114241424222222'],['Ice','242221422222422242'],['Fighting','222222222441122124'],['Poison','222212114241222221'],['Ground','224044212222122222'],['Flying','222414120221422222'],['Psychic','222222122214242422'],['Bug','242212121422422222'],['Rock','114242414122222242'],['Ghost','022222012221242422'],['Dragon','211114222222224224'],['Dark','222222422204212124'],['Steel','142211404111121211'],['Fairy','222222142221220142']
L=[]
for x,X in i:
 for y,Y in i[i.index([x,X]):]:
  S=W=0.
  for a,b in zip(X,Y):A=int(a)*int(b);W+=A&gt;4;S+=A&lt;4
  L+=[([x+'/'+y,x][x==y]+' -&gt; %d/%d'%(S,W),S/W)]
for l in sorted(L, key=lambda l:-l[1]):print'%s = %.2f'%l


Outputs:

Bug/Steel -&gt; 9/1 = 9.00
Steel/Fairy -&gt; 11/2 = 5.50
Normal/Ghost -&gt; 5/1 = 5.00
Water/Ground -&gt; 5/1 = 5.00
Grass/Steel -&gt; 10/2 = 5.00
Poison/Dark -&gt; 5/1 = 5.00
Poison/Steel -&gt; 10/2 = 5.00
Flying/Steel -&gt; 10/2 = 5.00
Dragon/Steel -&gt; 10/2 = 5.00
Normal/Steel -&gt; 12/3 = 4.00
Electric/Poison -&gt; 8/2 = 4.00
Electric/Steel -&gt; 12/3 = 4.00
Ghost/Dark -&gt; 4/1 = 4.00
Water/Steel -&gt; 11/3 = 3.67
Dark/Steel -&gt; 11/3 = 3.67
Steel -&gt; 11/3 = 3.67
Fire/Steel -&gt; 10/3 = 3.33
Fire/Ground -&gt; 6/2 = 3.00
Water/Flying -&gt; 6/2 = 3.00
Electric -&gt; 3/1 = 3.00
Electric/Flying -&gt; 6/2 = 3.00
Electric/Fairy -&gt; 6/2 = 3.00
Ice/Steel -&gt; 9/3 = 3.00
Fighting/Steel -&gt; 9/3 = 3.00
Rock/Steel -&gt; 9/3 = 3.00
Ghost/Steel -&gt; 12/4 = 3.00
Fire/Electric -&gt; 8/3 = 2.67
Water/Poison -&gt; 8/3 = 2.67
Normal/Poison -&gt; 5/2 = 2.50
Water/Electric -&gt; 5/2 = 2.50
Poison -&gt; 5/2 = 2.50
Ground/Flying -&gt; 5/2 = 2.50
Ground/Steel -&gt; 10/4 = 2.50
Psychic/Steel -&gt; 10/4 = 2.50
Fire/Flying -&gt; 7/3 = 2.33
Water/Fairy -&gt; 7/3 = 2.33
Electric/Ghost -&gt; 7/3 = 2.33
Normal/Electric -&gt; 4/2 = 2.00
Normal/Fairy -&gt; 4/2 = 2.00
Fire -&gt; 6/3 = 2.00
Fire/Poison -&gt; 8/4 = 2.00
Fire/Bug -&gt; 6/3 = 2.00
Fire/Fairy -&gt; 8/4 = 2.00
Water -&gt; 4/2 = 2.00
Water/Ghost -&gt; 8/4 = 2.00
Electric/Bug -&gt; 4/2 = 2.00
Fighting/Poison -&gt; 6/3 = 2.00
Poison/Fairy -&gt; 6/3 = 2.00
Psychic/Ghost -&gt; 4/2 = 2.00
Ghost -&gt; 4/2 = 2.00
Ghost/Fairy -&gt; 4/2 = 2.00
Dragon/Fairy -&gt; 8/4 = 2.00
Fairy -&gt; 4/2 = 2.00
Fire/Ghost -&gt; 9/5 = 1.80
Normal/Fire -&gt; 7/4 = 1.75
Fire/Rock -&gt; 7/4 = 1.75
Fire/Dark -&gt; 7/4 = 1.75
Poison/Dragon -&gt; 7/4 = 1.75
Normal/Water -&gt; 5/3 = 1.67
Fire/Water -&gt; 5/3 = 1.67
Fire/Dragon -&gt; 5/3 = 1.67
Water/Bug -&gt; 5/3 = 1.67
Electric/Fighting -&gt; 5/3 = 1.67
Ghost/Dragon -&gt; 8/5 = 1.60
Fire/Fighting -&gt; 6/4 = 1.50
Water/Dragon -&gt; 3/2 = 1.50
Electric/Dragon -&gt; 6/4 = 1.50
Electric/Dark -&gt; 6/4 = 1.50
Poison/Ground -&gt; 6/4 = 1.50
Poison/Flying -&gt; 6/4 = 1.50
Poison/Rock -&gt; 6/4 = 1.50
Poison/Ghost -&gt; 6/4 = 1.50
Ground/Fairy -&gt; 6/4 = 1.50
Flying/Dragon -&gt; 6/4 = 1.50
Rock/Fairy -&gt; 6/4 = 1.50
Fire/Psychic -&gt; 7/5 = 1.40
Water/Fighting -&gt; 7/5 = 1.40
Water/Dark -&gt; 7/5 = 1.40
Grass/Fairy -&gt; 7/5 = 1.40
Fighting/Dragon -&gt; 7/5 = 1.40
Dragon/Dark -&gt; 7/5 = 1.40
Normal/Flying -&gt; 4/3 = 1.33
Fire/Grass -&gt; 4/3 = 1.33
Fighting/Dark -&gt; 4/3 = 1.33
Poison/Psychic -&gt; 4/3 = 1.33
Ground/Dragon -&gt; 4/3 = 1.33
Flying -&gt; 4/3 = 1.33
Dragon -&gt; 4/3 = 1.33
Dark/Fairy -&gt; 4/3 = 1.33
Normal/Dragon -&gt; 5/4 = 1.25
Water/Rock -&gt; 5/4 = 1.25
Electric/Ground -&gt; 5/4 = 1.25
Electric/Psychic -&gt; 5/4 = 1.25
Electric/Rock -&gt; 5/4 = 1.25
Grass/Poison -&gt; 5/4 = 1.25
Fighting/Bug -&gt; 5/4 = 1.25
Fighting/Ghost -&gt; 5/4 = 1.25
Poison/Bug -&gt; 5/4 = 1.25
Flying/Dark -&gt; 5/4 = 1.25
Water/Psychic -&gt; 6/5 = 1.20
Grass/Ghost -&gt; 6/5 = 1.20
Ground/Ghost -&gt; 6/5 = 1.20
Flying/Rock -&gt; 6/5 = 1.20
Flying/Ghost -&gt; 6/5 = 1.20
Flying/Fairy -&gt; 6/5 = 1.20
Bug/Ghost -&gt; 6/5 = 1.20
Bug/Fairy -&gt; 6/5 = 1.20
Normal -&gt; 1/1 = 1.00
Normal/Fighting -&gt; 4/4 = 1.00
Normal/Ground -&gt; 4/4 = 1.00
Normal/Psychic -&gt; 2/2 = 1.00
Normal/Bug -&gt; 3/3 = 1.00
Normal/Rock -&gt; 5/5 = 1.00
Normal/Dark -&gt; 3/3 = 1.00
Fire/Ice -&gt; 4/4 = 1.00
Water/Grass -&gt; 3/3 = 1.00
Electric/Grass -&gt; 4/4 = 1.00
Grass/Fighting -&gt; 6/6 = 1.00
Grass/Dark -&gt; 7/7 = 1.00
Ice/Poison -&gt; 5/5 = 1.00
Ice/Ghost -&gt; 5/5 = 1.00
Ice/Fairy -&gt; 4/4 = 1.00
Fighting -&gt; 3/3 = 1.00
Fighting/Flying -&gt; 5/5 = 1.00
Fighting/Fairy -&gt; 5/5 = 1.00
Ground -&gt; 3/3 = 1.00
Ground/Bug -&gt; 4/4 = 1.00
Ground/Rock -&gt; 6/6 = 1.00
Ground/Dark -&gt; 6/6 = 1.00
Psychic/Dragon -&gt; 6/6 = 1.00
Psychic/Fairy -&gt; 3/3 = 1.00
Bug -&gt; 3/3 = 1.00
Bug/Dragon -&gt; 5/5 = 1.00
Bug/Dark -&gt; 5/5 = 1.00
Rock/Ghost -&gt; 6/6 = 1.00
Rock/Dark -&gt; 7/7 = 1.00
Dark -&gt; 3/3 = 1.00
Grass/Psychic -&gt; 6/7 = 0.86
Fighting/Rock -&gt; 6/7 = 0.86
Normal/Grass -&gt; 5/6 = 0.83
Grass/Bug -&gt; 5/6 = 0.83
Fighting/Ground -&gt; 5/6 = 0.83
Ground/Psychic -&gt; 5/6 = 0.83
Rock/Dragon -&gt; 5/6 = 0.83
Grass -&gt; 4/5 = 0.80
Grass/Flying -&gt; 4/5 = 0.80
Flying/Psychic -&gt; 4/5 = 0.80
Flying/Bug -&gt; 4/5 = 0.80
Rock -&gt; 4/5 = 0.80
Electric/Ice -&gt; 3/4 = 0.75
Grass/Ground -&gt; 3/4 = 0.75
Ice/Flying -&gt; 3/4 = 0.75
Ice/Bug -&gt; 3/4 = 0.75
Psychic/Rock -&gt; 5/7 = 0.71
Grass/Dragon -&gt; 4/6 = 0.67
Ice/Rock -&gt; 4/6 = 0.67
Ice/Dark -&gt; 4/6 = 0.67
Fighting/Psychic -&gt; 2/3 = 0.67
Psychic -&gt; 2/3 = 0.67
Psychic/Bug -&gt; 4/6 = 0.67
Bug/Rock -&gt; 2/3 = 0.67
Ice/Dragon -&gt; 3/5 = 0.60
Grass/Ice -&gt; 4/7 = 0.57
Normal/Ice -&gt; 2/4 = 0.50
Water/Ice -&gt; 2/4 = 0.50
Grass/Rock -&gt; 2/4 = 0.50
Ice/Fighting -&gt; 3/6 = 0.50
Psychic/Dark -&gt; 1/2 = 0.50
Ice/Ground -&gt; 2/5 = 0.40
Ice/Psychic -&gt; 2/6 = 0.33
Ice -&gt; 1/4 = 0.25