If Ash and Brock, and Team Rocket travelled to Caldera/Kirant...

[OddCrow]

...Which pokemon do you think they'd catch?
Brock usually gets 3-4 and Ash usually gets a full team, and Jessie/James usually get one, maybe two each.

Ash -
Pikachu
Grific
Venap
Absol
Goldrake
Celsinge

Brock -
Whismur
Vixun
Gargoth
Smallard

Jessie -
Equill

James -
Jackalant

Picking brock's was hard, as I also considered Skalloy and Inflare.

[NyteFyre]

Inflare over Smallard would work better...Smallard is a water type, they're not really Brock's thing....and yes, i do realize that Ludicolo and Marshtomp were part water, but Marshtomp was more Ground....and i have no clue about Ludicolo...also, Jessie's Seviper would more likely Evolve into Pythang, than her having an Equill...Equill seems more Ashes style, he always gets the main bird pokemon in each region...first, pidgeotto, then Tailow, and now Starly...Also, Skalloy would fit better over Whismur, i'm not seeing where you're going with that one...but this is just my speculation...

[Cyndadile]

You've got to keep in mind that between Ash, Brock, and the third (female) person, they have all 3 of the starters of a region. Ash typically has 1/2, the girl will have 1, and Brock might have the last 1. Ash, I'm thinking Venap, Brock or Ash or girl=Celsinge, and Ash or girl=Echoise. Also, James will get someone grass-type that will bite him, I agree with Jackalant, but it will probably evolve. Probably Drakodo for Jessie, and Seviper will evolve into Pythang.

[PokePoindexter]

Then explain:
1. Brock had a Ludicolo for awhile, as well as Marshtomp, Crobat, and several others that aren't of the Rock type.
2. James currently has/had a Mime Jr., which doesn't bite him at all and is Psychic-type.

[Cyndadile]

I didn't say that was ALL, just that is part of it. Remember, Victreebell, Cacknea, Carnivine. There is always one that does it, not necessarily all of them. Brock seems to prefer rock/ground, but he can have different types.

[Obtuse]

I followed some of the patterns noted on Bulbapedia regarding parties in regions, or stuff I noticed. And I decided to assume this would happen after Sinnoh, so I took a Sinnoh Pokemon here and there.

Ash:
Pikachu
Eaglair (Ash always has the native early-game bird)
Traplent line (He always has the grass starter as well. Could totally be another part of the line as well.)
Whispaw/Coroona (Seems like something Ash would have to me)
Mirust (Random)
Sirene (His last Pokemon is part of a one-evolution family. For coolness, let's say he reunites with his Lapras and it evolves. And then Ash gets to have the super cool new type of the region. And it seems like a reliable way to travel through that big ocean)

Brock:
Croagunk/Toxicroak (he seems rather attached to Croagunk), or Forretress if we pretend Sinnoh didn't happen.
Gargoth (he usually has a rock of some sort with him)
Vixun (He loves Vulpix after all)
Echoise line

Random Girl:
Celsinge line (to complete the group having all the starters thing)
The rest would depend on what this girl's purpose is, I suppose. Are there contests in these regions? I can't remember off-hand, but let's just assume there are.
Engil/Benengil (looks cute enough for contests)
Grific (looks cute)
Drakodo (cool enough for contests and the random strong Pokemon in her group)
Snarliger (absolutely adorable!)
Mogel (random)

Jessie:
Wobbuffet (given)
Pythang (evolved Seviper)
Equill/Tellure (Jessie's "oh my god that Pokemon is the cutest thing ever I must have that for a contest" Pokemon. I agree with OP, it does fit)

James:
Cacnea/Cacturne/Cackinge (evolved Cacnea. Let's say James trades Carnivine for Cacnea with Gardenia. Also fulfills the hurting grass role. Doesn't necessarily need to be biting)
Spidream (James's cute baby Psychic type that will never battle ever)

[OddCrow]

Any other opinions on this matter?

I really think Brock would get Gargoth, Vixun, Smallard and Whismur.
He gets his
Rock-Type
Water-Type
Cute normal type
and his Baby pokemon.\

[NyteFyre]

i don't remember him really having a normal type before... :/

personally, i think he would get reefrain, or Cascadet over smallard, and maybe Cirroft for the normal type, that way he still get's the cute normal type, but it's from C/K only.

[Silver]

how 'bout this:

--- = instead of
evo. from = you Knowwhat is

ash:
pikachu
fincherp---starley
celsinge---chimchar
lupine---turtwig
trillogill---buizel
sinestill---gible

oddcrow's idea is perfect for brock

Random Girl:
Snarliger
Mogel
echoise
huskii[always figting ash's lupine]
stribra
engil


Jessie:
Wobbuffet
Pythang evo. from seviper
skarmory---yanmega

james:
dionare[childhood freind 'bites james']---carnavine
barkub---mime jr.
cacturnne

there happy?