What are the most defensive types in Pokemon?

My Pokemon team, at the moment, has a lot of offensive heroes, but lacks quite a bit in defense. So, which types are the most defensive? (which types have the most immunities/resistances)

Short Answer: Steel Pokemon have the most resistances, and high defensive stats too. Many pokemon have only 1 weakness, but Eelektross has zero due to its ability, and can be aquired in Pokemon Sun and Moon using the Island Scan on Poni Island on Sunday.

Full answer in terms of both Monotype and Dual-Type pokemon, and looking at Abilities as well.

First Monotype pokemon

Types with the most Resistances and Immunities

• Steel: 11
• Fire: 6
• Poison: 5
• Poison with Levitate Ability: 6 (Weezing)

Types with the fewest Weaknesses

• Normal: 1 (Fighting)
• Electric: 1 (Ground)
• Electric with Levitate Ability: 0 (Eelektross)
• Water with Lightning Rod Ability: 1 (Grass weakness, Hidden Ability Seaking)

Types with most Net defenses (Resistances and Immunities minus Weaknesses)

• Steel: 8
• Fire: 3
• Poison: 3
• Poison with Levitate Ability: 5 (Weezing)
• Water with Lightning Rod Ability: 4 (Hidden Ability Seaking)

There are a significant number of dual-type combinations, so this list will be less exhaustive. Below are notable Dual Types with particularly few Weaknesses, or many Resistances. Note that most dual steel types have many resistances.

• Dark/Ghost - 4 Resistances/Immunities, 1 Weakness (Spiritomb and Sableye)
• Dark/Poison - 5 Resistances/Immunities, 1 Weakness (Alolan Muk, Skuntank, Drapion)
• Water/Ground- 5 Resistances/Immunities, 1 Weakness (Swampert, Seismitoad, Gastrodon (has 1 more resistance with Storm Drain Ability)
• Steel/Bug - 9 Resistances/Immunities, 1 Weakness (Forretress, Genesect)
• Electric/Water with Levitate - 6 Resistances/Immunities, 1 Weakness (Rotom Wash)
• Electric/Fire with Levitate - 9 Resistances/Immunities, 2 Weaknesses (Rotom Heat)
• Steel/Ghost - 12 Resistances/Immunities, 4 Weaknesses (Aegislash)

Special Mention of Shedinja, due to Wonder Guard granting it 13 immunities, and only 5 weaknesses

I'll give you the best defensive Pokémon by type.

Type combinations with the least amount of weaknesses:

• Normal(61 Pokémon) e.g. Snorlax or Regigigas
• Electric (27 Pokémon) e.g. Normal Raichu or Electabuzz
• Normal/Ghost (0 Pokémon) Nonexisting
• Water/Ground (10 Pokémon) e.g. (Mega) Swampert or Gastrodon
• Poison/Dark (3 Pokémon) e.g. Skuntank or Drapion
• Bug/Steel (7 Pokémon) e.g. Forretress or Genesect
• Ghost/Dark (3 Pokémon) e.g. (Mega) Sableye or Spiritomb