What is the difference between a Primary type and a Secondary type?

Question

So I was looking on bulbapedia at Steel types just now (Not sure why, but I was) and I saw that on the Bulbapedia page on Steel types is has 2 lists of all the Steel type Pokemon. One list says "Primary Steel-type Pokémon" and another says "Secondary Steel-type Pokémon", my question is, what is the difference between a Primary type and a Secondary type other than the fact that Prmary types are listed first?

Comments

Primary types are the main types of a Pokemon. For example, Flygon's primary type is Ground
Secondary types are the other type. For exapmle, Zygarde's SECONDARY type is ground

When you see a Pokemon's type, it always goes like this: Primary-Secondary

Answer 1

The primary type is used for Revelation Dance when used by a Dual type Pokemon.

When Flying press is used on a Pokemon with Color Change, the opponent becomes a Fighting type, not a Fighting-Flying.

The secondary type of a Pokemon becomes it's primary type after using Burn Up.

In Gen 1, AI opponents can only see your primary type. In the case that Pineapple (thanks Pineapple,) gave, an AI will spam Toxic on the Bulbasaur line, thinking it's super effective, (another flaw of Gen 1 AI,) when in reality it does nothing, because Bulbasaur's second type is Poison.

So, unless your playing in Gen 1, and you are immune to certain moves because of your type, it doesn't really matter.

Answer 2

In Generation 2, there was a glitch involving present.

In Gold and Silver (and any link battle with either of them), a glitch causes the level, Attack, and Defense variables of the damage formula to be replaced. The Attack will be replaced with 10, while the level will be based on the index number of the defending Pokémon's type, and the Defense will be based on the index number of the attacking Pokémon's type (if a Pokémon has two types, its secondary type will be used).

source
Starting Generation 7, there's a move called revelation dance, and its user's primary type becomes the type of revelation dance.
source
Additionally, Pokemon Showdown! (a fansite) sometimes hosts two formats called Same Type Stealth Rock and Mix and Mega.
more on STSR
more on M&M

Answer 3

Primary types are types that a Pokemon has two of but,their main type is first,a secondary type is a type a Pokemon has two of, but their main type is second, like ,like Kyurem.Primary types are listed first because it is the Pokemon`s type,and can be classed as a steel type,a secondary type is two types that can be classed as a dragon AND an ice type.

Comments

I am asking what the difference is, not what they are, like, why does it matter what order they are in?

---

No, It really doesn't matter, It's only for classafication purposes.

---

Lol, NJDevil, your last activity before this comment was in December 2011 xD

Answer 4

Well, the first type is the main type meaning that is the type the pokémon looks like (bulbasaur grass-poison but looks grass ,flygon dragon -ground but looks dragon ).this is for one-type pokes too.moreover two types may make the pokémon more weak or less depents on the opponent pokémon .furthermore gamefreak can describe better a pokémon character putting two types (not only what it looks like but what it is able to do ).two types are made for better gaming and battling experience .also a player can create more battle strategies and a pokémon is able to have a bigger movepool .