We sorted the Hoenn Region Pokémon after the official National Pokédex:

 

#252

Treecko

#253

Grovyle

#254

Sceptile

#255

Torchic

#256

Combusken

#257

Blaziken

#258

Mudkip

#259

Marshtomp

#260

Swampert

#261

Poochyena

#262

Mightyena

#263

Zigzagoon

#264

Linoone

#265

Wurmple

 

#266

 Silcoon

#267

Beautifly

#268

Cascoon

#269

Dustox

#270

Lotad

#271

Lombre

#272

Ludicolo

 

#273

Seedot

#274

Nuzleaf

#275

Shiftry

#276

Taillow

#277

Swellow

#278

Wingull

 

#279

Pelipper

#280

Ralts

#281

Kirlia

 #282

Gardevoir

#283

Surskit

#284

Masquerain

#285

Shroomish

#286

Breloom

#287

Slakoth

#288

Vigoroth

#289

Slaking

#290

Nincada

#291

Ninjask

#292

Shedinja

#293

Whismur

#294

Loudred

#295

Exploud

#296

Makuhita

#297

Hariyama

#298

Azurill

#299

Nosepass

#300

Skitty

#301

Delcatty

#302

Sableye

#303

Mawile

#304

Aron

#305

Lairon

 

#306

Aggron

#307

Meditite

#308

Medicham

#309

Electrike

#310

Manectric

#311

Plusle

#312

Minun

#313

Volbeat

#314

Illumise

#315

Roselia

#316

Gulpin

#317

Swalot

#318

Carvanha

#319

Sharpedo

 #320

Wailmer

#321

Wailord

#322

Numel

#323

Camerupt

#324

Torkoal

#325

Spoink

#326

Grumpig

#327

Spinda

#328

Trapinch

#329

Vibrava

#330

Flygon

#331

Cacnea

#332

Cacturne

 

#333

Swablu

#334

Altaria

#335

Zangoose

#336

Seviper

#337

Lunatone

#338

Solrock

#339

Barboach

#340

Whiscash

#341

Corphish

#342

Crawdaunt

#343

Baltoy

#344

Claydol

#345

Lileep

 #346

Cradily

#347

Anorith

#348

Armaldo

#349

Feebas

#350

Milotic

#351

Castform

#352

Kecleon

#353

Shuppet

#354

Banette

#355

Duskull

#356

Dusclops

#357

Tropius

#358

Chimecho

#359

Absol

#360

Wynaut

 #361

Snorunt

#362

Glalie

#363

Spheal

#364

Sealeo

#365

Walrein

 #366

Clamperl

#367

Huntail

#368

Gorebyss

#369

Relicanth

 #370

Luvdisc

#371

Bagon

#372

Shelgon

#373

Salamence

#374

Beldum

#375

Metang

#376

Metagross

#377

Regirock

#378

Regice

#379

Registeel

#380

Latias

#381

Latios

#382

Kyogre

 #383

Groudon

#384

Rayquaza

#385

Jirachi

#386

Deoxys

 
 
 

Some Trivia regarding our 3rd Pokemon Art Collaboration:

The first three Gen III Pokemon that were claimed for our art collaboration were:

Sceptile with Leaf Blade by Kiriko-Windgeist around 15 minutes
Seviper using Poison Tail by BlazeTBW 18 minutes 
Absol doing Night Slash by LukeTheRipper 20 minutes
…after the Blogpost for our new project was online

The first three drawn and submitted Gen III Pokemon were:
Sceptile with Leaf Blade by Kiriko-Windgeist on the 1st January already
Pelipper using Hydro Pump by Yggdrassal  on the 1st January already as well
Delcatty using Water Pulse by AuroraLion on the 2nd January

The first Pokemon claimed by two artists was Spheal on the 1st January

Latias was the first Gen III Pokemon that goth both artworks drawn for this collaboration.

The 2nd illustration was done at the 14th January.

35 Artists joined the Gen III Tribute on the 1st January already, however it was difficult to get the last around 90 illustrations together.