Saffron City is the eighth city a trainer will encounter. The city's Gym Leader is Sabrina, a professional-type Pokémon trainer. Yellow buildings are home to citizens though, you cannot enter them.
Saffron Gym is a-type Gym led by Sabrina as the Gym Leader. She will be seen floating in the air when you enter the Gym. You will not have to battle another trainer.
The Bot Lab is an area where you can battle any player that has the Champion badge. The Bot Lab is a great way to grind for EXP in the game. Though, you will not earn any Pokédollars when you defeat the bot. You can find it on the right of the PokéCenter. Please click here for more information.
The Fighting Dojo used to be the Gym at Saffron City until Sabrina came in. (is weak against ) Inside you will find many black belt NPCs that will battle you with -type Pokémon. After you defeat the two special NPCs with a green and a red headband in the back, they will reward you with either a Hitmonlee or a Hitmonchan, which are both level 45.
To get into the Snowy Canyon, Justin Justice from the Police Station in Celadon City asks you to find "Santa" on top of a house in Saffron City. When you defeat him, you can finally enter Snowy Canyon, guarded by an admirer of his.
You can obtain Ho-Oh and Heatran in Saffron City's PokéCenter. For Ho-Oh you must have: Mr.Mime, Jynx, Lickitung, Metagross, and an empty slot in your party. Heatran will be given by Professor Oak if you have 300 Pokédex entries.
*Both Hitmonchan and Hitmonlee will be lvl 45 when received, regardless of your badge progress.