Notes on remaining type combinations

Dual types that are not part of Bug, Normal, Fairy or Poison:

1. Grass/Fire
2. Ground/Fighting
3. Ghost/Rock
4. Electric/Fighting

Dual types that are part of Bug, Normal, Fairy or Poison:

1. Normal/Steel
2. Ice/Normal
3. Ice/Poison
4. Bug/Dark
5. Bug/Dragon
6. Fairy/Fire
7. Fairy/Ground
8. Fairy/Fighting
9. Poison/Steel
10. Normal/Rock

Dual type combinations that are both Bug, Normal, Fairy or Poison:

1. Normal/Poison
2. Bug/Normal

Grass only needs Grass/Fire to complete.

Dragon only needs Dragon/Bug to complete.
Electric only needs Electric/Fighting to complete.
Fire only needs Fairy/Fire to complete.
Dark only needs Bug/Dark to complete.

Ghost only needs Ghost/Rock to complete.

Fighting will only have one after completing the first four.

Ground will only have one after completing the first four.

Rock will only have one after completing the first four.

Steel will only have two after completing the first four.

Ice will still have two remaining.

Edit (27.11.2019): Updated for Sword/Shield.
Edit (20.06.2020): Added Galarian Slowbro's Poison/Psychic.

Edit (25.10.2021): Added Hisuian Zorua/Zoroark's Normal/Ghost.