Which Pokemon types do you believe are essential to a team?

Basically as the title says, what type of Pokemon should make up your team? (Obviously meaning six Pokemon, including, and not including a starter.)

I say Dragon because it isn't very effective against other types only dragon and ice (correct me if i'm wrong) besides if i remember correctly dragon type pokemon can pretty much learn every move type, thunder,fire,ground, etc.

5 out of my 6 are Psychic type and the 1 that isnt was given TM29 (Psychic) thanks to Gallade and my Giratina slaying Bronzong+Girafarig duo our and the non-Psychic type Manaphy our weaknesses are covered

IMO, the Water type is the most essential type a team can have. It can learn powerful moves that aren't resisted by that many, and has only two weaknesses which is easily countered, especially if the pokemon in question has a dual type which removes one of the weaknesses, such as Quagsire and Gyarados.
Also, I find myself using the Fighting type a lot too, due to it's handy resistances and powerful attacks.

Fire
Water
Grass
Flying ( I wish there was a way to get from city to city quickly without fly -_-)

For me Dragon,Steel,Fire,Water and Psychic/Ghost are the types which are essential to a team.

I think it would be Water, Dragon, Ghost/Dark, Fighting and Fire (perhaps Ice) - Water is good for SE hitting many types, Dragon is unresisted except steel, Fire destroys that steel (barring Heatran), whereas Fighting and Ghost/Dark is completely unresisted

In my team, I use Dragon, Steel, Fire, Water, Grass, and Physcic.

My team if not always has a Fire, Water, Grass, and Electric type.
My last two pokemon are whatever kind I want. Usually one of them
is an Ice type.

I use Dragon, Water, Electric, Fire, and Grass. My water type and my dragon type are most important, though.

I find Fire, Water, Electric and possibly Rock, Ground or Flying extremely useful.

Flying, Electric, Fire, Water, Ground, Psychic and maybe Dark

Ice is very useful to me because it is handy for dealing with pesky Dragons. Just about all the non-legendary Dragons are 4x weak to Ice.

Steel is another type I find essential due to it resistance to 11 types. I use at least one of them for resisting Dragon type attacks which only Steel can do.

I usually have a Water Pokemon on most of my teams because most of them are capable of using Ice attacks and Water moves are only resistant to two types not including Water types themselves. I tend to use dual-water type Pokemon such as Swampert for more coverage.

Hm...

Water and/or Grass, Fire and/or Fighting, Ground and/or Rock, Dragon and/or Steel, Ghost and/or Dark, and Bug or Psychic, with subtypes of whatever

I don't usually care that much, since with Porygon, typing is not an issue! (Conversion2 is actually much more useful then it seems.)

But I have found that when not working with my familiar team, a trusty flying type is always good to have with you, In fact, in each of my games from Blue to Platinum, I've had at least one bird partner:

Blue: Fearow
Yellow: Pidgeot
Crystal: Noctowl
Sapphire: Swellow
LeafGreen: Pidgeot
Diamond: Staraptor
Pearl: Altaria
Platinum: Togekiss

Dragon. They have many strengths and few weaknesses. I always have at least one if not more on my team

in-game?

Fire
Water
Flying
Fighting
Dragon
Psychic
Dark
Ground
Rock

more than six...so the PKMN would have to have types like these

Fire/Fighting
Ground/Rock
Water
Dragon/Flying
Dark
Psychic

Well, I almost always have a water type and a flying type, to be HM slaves :D I always like having a normal type as well, for some reason >.<

Insert random filler here.

I don't care what type as long as my pokemon are fast and have a 1 hit KO. ;)