OK, first, I'm gonna need updated art of the following overall:
* Red and Leaf (the protagonists), in a look that appears to be a cross between their Red/Blue appearances (technically speaking, though, the latter didn't appear in any Gen I games, though my pokered hack does include an option to play as her, based on how she appeared in supplementary material made around that time) and their FireRed/LeafGreen appearances;
* Blue (the rival), sporting a look close to how he appeared in FireRed/LeafGreen;
* The Gym Leaders, with the following designs:
- Brock: White T-shirt, canvas pants, and rubber boots;
- MIsty: Picnicker uniform, consisting of a blue cap, a blue short-sleeved shirt, a light blue tie, blue shorts, light blue tights, and black Mary Janes (similar to the Picnicker uniform in Gold/Silver/Crystal and FireRed/LeafGreen);
- Lt. Surge: Camouflage army uniform, consisting of a shirt with rolled-up sleeves, pants, and boots;
- Erika: A kimono with red hakama;
- Koga: A black and purple ninja uniform;
- Sabrina: An outfit similar to that she wears in the first three generations;
- Blaine: Similar to his prototype looks, with balding grayish-red hair and neither sunglasses nor facial hair, with a Hawaiian shirt and cargo pants; and
- Giovanni: His suit from Red/Blue/Yellow and FireRed/LeafGree, but without the Rocket badge, and with the fedora he wears in HeartGold/SoulSilver and Black2/White2;
* Professor Oak, looking more or less like he does in Red/Blue/Yellow and FireRed/LeafGreen;
* The Elite Four, with their FireRed/LeafGreen appearances more or less;
* The following individual trainer classes, with the following looks:
- Youngster: Gold backwards baseball cap, blue T-shirt, jean shorts, and blue sneakers;
- Gentleman: Brown suit with a matching bowler hat, kinda like in Omega Ruby/Alpha Sapphire but less saturated colorwise;
- Sailor: Similar to his Omega Ruby/Alpha Sapphire looks, but with a blue tie;
- Lass: A white short-sleeved shirt, a blue pleated skirt, white baggy kneesocks, and brown shoes;
- Bug Catcher: A slouch hat, a white tank top, blue shorts, and blue and white shoes;
- Rocket Grunt♂: A black cap, a black long-sleeved jacket with the red R on the front, black pants, and black boots;
- Rocket Grunt♀: A black cap, a black long-sleeved jacket with the red R on the front worn over a black skirted leotard, black tights, and black boots;
- Camper: A khaki cap, a khaki short-sleeved shirt, a blue tie, khaki shorts, white crew socks, and black Mary Janes;
- Picnicker: A khaki cap, a khaki short-sleeved shirt, a pink tie, khaki shorts, white kneesocks, and black Mary Janes;
- Fisherman: Dressed exactly like his Omega Ruby/Alpha Sapphire counterpart;
- Hiker: An alpinist's hat, a blue short-sleeved shirt, a khaki vest, khaki pants, and brown hiking boots;
- Swimmer♂: A blue bathing cap, blue gogles, and a blue bikini-cut speedo;
- Swimmer♀: A pink bikini;
- Beauty: A white T-shirt, blue gym bloomers, and white ballet flats;
- Rocker: A blue knit cap, a red leather jacket, a white T-shirt, blue jeans, and rubber boots;
- Engineer: A yellow hard hat, a yellow jumpsuit, and rubber boots;
- Ace Trainer♂: A white polo shirt, white pants, and white boots;
- Ace Trainer♀: A white polo shirt, a white miniskirt, black bike shorts, and white boots;
- Pokémaniac: A Charizard-style hat, a white labcoat, a black T-shirt, and the lower half of a Charizard suit;
- Black Belt: A white karate uniform;
- Juggler: A blue bandana, a blue cape, a black waistcoat, a white long-sleeved shirt, black pants, and black shoes;
- Tamer: A jean jacket, a black shirt, blue jeans, and black boots;
- Bird Keeper: Jean overalls over a red shirt and brown shoes;
- Channeler: A kimono with white hakama pants;
- Psychic: A blue jumpsuit with a gold waistband and blue shoes;
- Hex Maniac: A black witch hat, a black cape, a black longcoat, a black T-shirt, black pants, and black Mary Janes;
- Fairy Tale Girl: A pink hair bow, a pink dress with poofy sleeves, a pinafore, and petticoats; white tights, and black Mary Janes;
- Scientist: Glasses, a white labcoat, a white shirt, a blue tie, black pants, and black shoes;
- Gambler (Private Investigator): A brown fedora, a brown trenchcoat, a white shirt, a red tie, black pants, and brown shoes;
- Super Nerd: Glasses, a white short-sleeved shirt, black pants, and black shoes;
- Burglar: A white backwards cap, a white short-sleeved shirt, a black long-sleeved undershirt, khaki pants, and black sneakers;
- Biker: A brown scarf, a black leather vest, ripped jeans, and brown motorcycle boots;
- Roughneck: A black leather jacket, a black T-shirt, blue jeans, and brown boots;
- Crush Girl: An orange tracksuit, black fingerless gloves, and black ballet flats;
- Tuber♂: Blue swim trunks;
- Tuber♀: A pink skirted swimsuit;
- Twins: A blue sleeveless dress, dark blue leggings, white bobby sox, and black Mary Janes;
- Young Couple (man): A white hoodie with a right-facing Luvdisc printed on it, pink jeans, and white sneakers;
- Young Couple (woman): A white hoodie with a left-facing Luvdisc printed on it, a pink skirt, black bike shorts, and white sneakers;
- Aroma Lady: A pink short-sleeved jacket worn over a pink long-sleeved leotard, a lavender and white skirt with petticoats, and pink ballet flats;
- Painter: A black beret, a white T-shirt, black pants, and red ballet flats;
- Pokémon Breeder: A green bandana, a green apron worn over a white T-shirt, khaki pants, and red sneakers;
- Pokémon Ranger♂: A red cap, a red vest worn over a black T-shirt, black pants, and red boots;
- Pokémon Ranger♀: A red cap, a red vest worn over a black T-shirt, black shorts, and red boots; and
- Ruin Maniac: A khaki pith hat, a khaki shirt, khaki pants, and black boots;
* Bill, wearing his FireRed/LeafGreen costume
I apologize if all this is too much, but if it is, please concentrate on just a few at a time.