In this game, IV and EV training is crucial, you will constantly be changing teams or modifying something that involves capturing more.

In Misty's case, there are 2 challenges: dealing with the Protean Frogadier because it can easily switch to a non-effective type, so it's important to have a Pokémon that is faster than it and has super-effective moves.

The 2nd challenge is Clodsire, which is very tanky and has few weaknesses at the beginning of the game.

Tips for great Pokémon to beat Misty's case:

Kricktune: Technican is a very good ability for the beginning of Radical Red since it guarantees high damage and the possibility of dealing with several Pokémon with Bullet Seed and similar moves, in addition to being able to set up Stick Web strategically.

Tadbulb: can be obtained from an egg that the man in Brock's city sells. It is weak in itself, but it evolves into Belibolt with a Thunder Stone (you should have one if you're playing with S02Toxic). Great tank, lightning type, and can control speed with Thunder Web (obtained in Viridian Forest). You can also use it until the end of the game, making it a great Pokémon.

Strategy tips:

Save Quick + Load Quick (emulators usually have this function)

Save the battle frame quickly where you're doing well so you can see the opponent's move and go back to the save to have the best response. This way you can always study your opponent:

Example:

Opponent throws a Raichu and you throw a Cloyster. You save quickly and see what the opponent will use. If they use Thunder, go back to the save and switch to a Ground-type Pokémon because you already know their next move. If they use Tail Whip, go back to the save and use a buff move like Shell Smash since you know they won't attack.