The first Pokémon of each type combination : r/pokemon

A chart with what type combinations are missing and an example for each comb there is already - 9GAG

Top 5 Strongest Type Combos

Unused type combinations Gen VI : r/pokemon

Pokémon: The 10 Most Interesting Unique Type Combinations, Ranked

Unused type combinations Gen V by AdeptCharon on DeviantArt

Pokemon: The 10 Best Type Combinations That Have Never Been Used

Type Combinations for Pokemon X and Y

9 Unused Type Combinations After SV by Fakemon1290 on DeviantArt

I made 3 Pokemon with some of the worst type combinations, are they any good? : r/stunfisk

Crystal Mind — celesteela: Unused type combinations for Pokémon