An alternate story

Celadon mistakes

We can skip to when Ash, Yellow and Brock arrive at Celadon city. The events of the ss Anne don't happen since team rocket aren't here to give the gang tickets, Bye bye butterfree remains the same with Ash releasing Butterfree and instead of catching a pissed off Primape that got mad when team ticket kicked him Ash catches a Mankey. So currently Ash's team is looking like:
Eevee:
Take down
Protect
Dig
Iron tail

Pidgeotto:
Gust
Quick attack
Steel wing
Whirlwind

Bulbasaur:
Vine whip
Leech seed
Solar beam
Stun spore

Charmander:
Flamethrower
Fire spin
Smokescreen
Scary face

Krabby:
Vice grip
Bubblebeam
Crab hammer
Water gun

Mankey:
Thrash
Mega kick
Scratch
Seismic toss

Ash finds him with his face against a store window, noticing several girls inside. Ash thinks Brock is wasting time and proceeds to leave, but Yellow and Eevee are revealed to be inside the perfume store, admiring the variety of aromas. Yellow asks about how much it will cost, but Ash steps inside and urges her not to waste her money. The female manager confronts Ash about his negative claim, but Ash pushes it further by saying all perfumes are a waste and turn guys into zombies, pointing to Brock. Everyone in the store is against Ash about his remark, even his own friends, and they kick him out. Ash storms away and heads to the Celadon Gym, but when he tries to enter, none of the Trainers are willing to let him in. They know about his perfume distaste since the perfume originates from the Gym. The lead Trainer stamps a red cross on Ash's face before kicking him out and closing the doors. Ash unfortunately doesn't have team rocket to help change him into Ashley which allowed him to sneak into the gym in the original canon so he just heads to the nearly route to start training his team while also thinking of a way to challenge the gym. However Yellow is able to challenge the gym leader.
Ref:This will be a 3 on 3 battle. The battle will be over once all 3 pokemon on either side are unable to battle.
(I believe that in the original series you weren't allowed to substitute pokemon)
Erika:Tangela I choose you!
Yellow:Doduo let's go!
Both pokemon are sent into battle.
Erika:Tangela use stun spore!
Yellow:Dodge and use peck!
Tangela sends a gust of yellow gas but Doduo leapt high into the air and avoids the attack. He then dives down starts to repeatedly peck at Tangela until the pile of vines faints
Ref:Tangela is unable to battle.
Erika returns her pokemon and then sends out Weepinbell.
Erika:Use vine whip!
Yellow:Use fury attack and peck!
Weepinbell's head root extended towards Doduo but the twin bird pokemon got out of the way and land the fury attack and peck combo taking out Weepinbell. Erika returns her Weepinbell as she sends out her ace Gloom. The flower unleashed a plume of stinky gas and Doduo is knocked out. Yellow then sends out Beedrill who I'd immune to the stinky fumes.
Erika:Use razor leaf!
Yellow:Twineedle attack!
Gloom sends leafs hurtling towards Beedrill but the Beedrill evades them all and starts barraging Gloom with vicious attacks until thr flower faints. Yellow is then given her rainbow badge as the doors burst open to reveal Ash.
Ash:Erika I demand you give me a gym battle!
Erika accepts the challenge and sets up a three-on-three battle. Ash sends out Bulbasaur while Erika sends out Tangela, which prompts Ash to check his Pokédex. Bulbasaur attacks with Vine Whip, but Tangela uses Constrict to pull Bulbasaur closer before following up with Stun Spore, paralyzing Bulbasaur. Ash recalls Bulbasaur and Erika offers to treat it with Parlyz Heal, but he refuses and sends out Charmander instead. Erika sends out Weepinbell and opens with a Razor Leaf attack. Charmander uses Flamethrower to stop the attack and send it back as fireballs. Charmander uses Skull Bash to knock out Weepinbell. Erika points out Ash's lack of empathy towards his Pokémon as she sends out Gloom. It releases its stench and upon smelling it, Charmander jumps into the air, holding its nose before fainting. Ash decided to use Mankey and his raw power was enough to overcome Gloom and win Ash the badge.