Why don't type specialist Champions only have Pokemon that are their type?

[Kathylikestoread]

Like, Iris has Aggron, Lapras and Archeops, Steven has Cardily, Claydol and Armando and Lance has Gyarados, Charizard, Seadra and Aerodactyl. While Lance's team is at least understandable, because of the lack of dragon type Pokemon in Generations I and II, but why Iris and Steven? Steven's team maybe is a reference to fossils, but why Iris? She could have had a Garchomp, Flygon and Altaria, but why did they give her Aggron, Lapras and Archeops? I get that they can learn dragon type moves, but only her Archeops has a dragon type move, dragon claw. And, it's not like Steven couldn't have had a Magneton/Magnezone either.

 

[Pigrider09]

1. Not many regions have enough of a singular type to make true monotype teams with 6 pokemon. So either a: you make a trainer with pokemon from other regions, which doesn’t really make sense for the top trainers of the region (maybe one or two pokemon from another reason is ok, but evens still 4-5 unique pokemon of a singular type is a lot for one region) or b. Just add pokemon that are similar enough to the theme type.

2. It’s too easy. It would be kinda lame if you could just overpower the top trainer of the region as long as you had one or two super effective coverage moves.

 

[RichestAirPirate]

Big answer incoming! Not all regions have enough Pokémon to make a monotype team of 6. So they settle for things that are close enough.

Lance is a Dragon type champion, but his champion teams only have 1 unique dragon type in the form of his 3 Dragonites. And Kingdra was already used by Clair. To compromise, Lance uses Pokémon that are dinosaur/reptilian/dragon-like, including 2 honorary dragon Pokémon, Charizard and Gyarados. Aerodactyl is based on a pterodactyl, which are known as winged dragons in Japan. Funnily enough, Lance even touches upon his usage of non dragon-type dragons in Pokémon Masters, where he states that not all dragon Pokémon are dragon type.

The RSE Pokédex doesn't have enough Steel types to fit a full team of 6, so instead, Steven's team makes a compromise by being a nod to his geology hobby. Plus, each team member makes sense for him to have when you think of it like that. He more than likely encountered most of those Pokémon as a result of his exploration of cave/rocky areas.

For Iris, the B2W2 Pokédex doesn't have enough Dragon-types to fill a whole team of 6, so she pulled a Lance and used Pokémon that are dinosaur/reptilian/dragon-like in order get a team of 6. Aggron is based on kaijus, Lapras is based on a plesiosaur, and Archeops is partially based on microraptors.

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However, another possible answer to your question, and this is more of an opinion but it'll make sense. The battles would've probably been too easy/difficult if those champions did use Pokémon only of their specialty type.

Steel and Dragon were incredibly strong back in Gens 2, 3, and 5. Steel because it resisted all but 5 types at the time and Dragon because only Steel resisted it, it was only weak to itself and ice, and Dragon type Pokémon tend to have high stats. If Lance, Steven, and Iris had monotype teams, they could've been easily sweepable for players that have Pokémon with STAB super effective damage or an absolute nightmare for players that didn't have the coverage. The latter especially applied to Dragon because of Ice being its only weakness if you didn't wanna risk using Dragon Pokémon yourself.

TLDR: They don't use full monotype teams because there aren't enough Pokémon of those types in the regional dex and possibly because it would be too easy/too hard for players to deal with monotype teams of the two strongest types.

 

[Unovia]

Big answer incoming! Not all regions have enough Pokémon to make a monotype team of 6. So they settle for things that are close enough.

Lance is a Dragon type champion, but his champion teams only have 1 unique dragon type in the form of his 3 Dragonites. And Kingdra was already used by Clair. To compromise, Lance uses Pokémon that are dinosaur/reptilian/dragon-like, including 2 honorary dragon Pokémon, Charizard and Gyarados. Aerodactyl is based on a pterodactyl, which are known as winged dragons in Japan. Funnily enough, Lance even touches upon his usage of non dragon-type dragons in Pokémon Masters, where he states that not all dragon Pokémon are dragon type.

The RSE Pokédex doesn't have enough Steel types to fit a full team of 6, so instead, Steven's team makes a compromise by being a nod to his geology hobby. Plus, each team member makes sense for him to have when you think of it like that. He more than likely encountered most of those Pokémon as a result of his exploration of cave/rocky areas.

For Iris, the B2W2 Pokédex doesn't have enough Dragon-types to fill a whole team of 6, so she pulled a Lance and used Pokémon that are dinosaur/reptilian/dragon-like in order get a team of 6. Aggron is based on kaijus, Lapras is based on a plesiosaur, and Archeops is partially based on microraptors.

---

However, another possible answer to your question, and this is more of an opinion but it'll make sense. The battles would've probably been too easy/difficult if those champions did use Pokémon only of their specialty type.

Steel and Dragon were incredibly strong back in Gens 2, 3, and 5. Steel because it resisted all but 5 types at the time and Dragon because only Steel resisted it, it was only weak to itself and ice, and Dragon type Pokémon tend to have high stats. If Lance, Steven, and Iris had monotype teams, they could've been easily sweepable for players that have Pokémon with STAB super effective damage or an absolute nightmare for players that didn't have the coverage. The latter especially applied to Dragon because of Ice being its only weakness if you didn't wanna risk using Dragon Pokémon yourself.

TLDR: They don't use full monotype teams because there aren't enough Pokémon of those types in the regional dex and possibly because it would be too easy/too hard for players to deal with monotype teams of the two strongest types.

Just to advance on this, there are 17 Champions.
Kanto: Blue & Trace
Johto: Lance & Red
Hoenn: Steven & Wallace
Sinnoh: Cynthia
Unova: Alder & Iris
Kalos: Diantha
Galar: Leon, Mustard, & Peony
Paldea: Nemona & Geeta
BB League: Kieran & Drayton

Of these, only Lance, Steven, Wallace, Iris, Peony, & Drayton are classified as "Type Specialist". Of those, only Wallace & Peony actually stick to their Type Specialty.

In Generation 1 & 2, the Dragon Type was limited to just the Dratini family. For Steven, he was also an explorer so they could branch him a bit more, since the Steel Type was limited to 8 families not including Legendaries. For Iris, she suffered from the same problem as Lance, having very few Dragon families, though with her, perhaps they could have done something.

Regardless, if the Champions had stayed Type bound, they likely would have been able to get swept. Pre Generation 6, Dragons were weak to Dragon & Ice, though since Generation 6, Fairy has been added. Steel has always been weak to Fighting, Fire, & Ground, common types for any Playthrough. If you ran with a Blaziken or Swampert, you could sweep. I suspect the reason that the Type bound ones did not stay type bound was to add more challenge as well as to give the Player, no matter the Starter, Pokemon they could defeat.

 

[RichestAirPirate]

Just to advance on this, there are 17 Champions.
Kanto: Blue & Trace
Johto: Lance & Red
Hoenn: Steven & Wallace
Sinnoh: Cynthia
Unova: Alder & Iris
Kalos: Diantha
Galar: Leon, Mustard, & Peony
Paldea: Nemona & Geeta
BB League: Kieran & Drayton

Of these, only Lance, Steven, Wallace, Iris, Peony, & Drayton are classified as "Type Specialist". Of those, only Wallace & Peony actually stick to their Type Specialty.

In Generation 1 & 2, the Dragon Type was limited to just the Dratini family. For Steven, he was also an explorer so they could branch him a bit more, since the Steel Type was limited to 8 families not including Legendaries. For Iris, she suffered from the same problem as Lance, having very few Dragon families, though with her, perhaps they could have done something.

Regardless, if the Champions had stayed Type bound, they likely would have been able to get swept. Pre Generation 6, Dragons were weak to Dragon & Ice, though since Generation 6, Fairy has been added. Steel has always been weak to Fighting, Fire, & Ground, common types for any Playthrough. If you ran with a Blaziken or Swampert, you could sweep. I suspect the reason that the Type bound ones did not stay type bound was to add more challenge as well as to give the Player, no matter the Starter, Pokemon they could defeat.

To add on to this again, it just makes logical sense for a Champion trainer to have a type diverse team.

You can't rely on one type of Pokémon for every situation after all.

 

[Bolt Strike]

Just to advance on this, there are 17 Champions.
Kanto: Blue & Trace
Johto: Lance & Red
Hoenn: Steven & Wallace
Sinnoh: Cynthia
Unova: Alder & Iris
Kalos: Diantha
Galar: Leon, Mustard, & Peony
Paldea: Nemona & Geeta
BB League: Kieran & Drayton

Of these, only Lance, Steven, Wallace, Iris, Peony, & Drayton are classified as "Type Specialist". Of those, only Wallace & Peony actually stick to their Type Specialty.

Another thing to notice is that all of the Type Specialists except Peony and Drayton are from earlier generations, and they're only nominally Champions because they held the title before the events of their respective games. They've definitely moved away from Type Specialist Champions in recent generations. The ones you actually fight as Champions from Gen 6 on are Diantha, Prof. Kukui/Hau (technically not Champions in Alola, but they take the place of the traditional Champion battle in the Alola games), Leon, Geeta, and Kieran. None of which are Type Specialists. They've definitely moved away from Type Specialist Champions gameplay wise, presumably for the reasons already outlined in this thread.

 

[RichestAirPirate]

Peony and Drayton

Another thing to note is that these guys aren't champions anymore and they specialize in the two strongest types that got nerfed in gen 6.