Switching Pokémon Mid-Battle: Not Possible Until Gen 2 (Gold/Silver)

You cannot switch Pokémon mid-battle in Pokémon Red/Blue/Yellow (Game Boy). The mechanic didn't exist yet.

How Gen 1 Battles Worked

• Single active Pokémon per trainer.
• When it faints, you must send another from party (no choice mid-turn).
• No "Switch" command in battle menu — only Fight / Bag / Pokémon / Run.
• "Pokémon" menu only usable outside battle to reorder party, use items, view stats.

What You CAN Do in Gen 1

• Pre-Battle Prep: Order party so lead matches upcoming gym/route.
• Item Healing: Potions, Revives, status heals from Bag during battle.
• Run Away: Escape wild battles (not trainers).

Switching Introduced in Generation 2

Pokémon Gold/Silver/Crystal (Game Boy Color) added:

• "Switch" option in battle menu (costs a turn).
• Held items (Leftovers, Berries).
• Day/night cycle, breeding, 100 new Pokémon.

Want Switching in Gen 1?

• ROM Hacks: Pokémon Red++, Blue Kaizo add QoL features including switch.
• Emulators (mGBA, BGB): Support cheat codes for "switch anytime" but breaks balance.
• Virtual Console (3DS): Official releases unchanged — no switching.

Recommendation: Play Gold/Silver/Crystal for the first "modern" Pokémon experience. They're on 3DS eShop (closing soon) and Nintendo Switch Online.