Pokemon HOME's FireRed and LeafGreen transfers are one-way
Pokemon HOME now supports FireRed and LeafGreen, but every transfer out of the games is permanent.
Pokémon HOME now links with Pokémon FireRed Version and Pokémon LeafGreen Version on Nintendo Switch, but the transfer is a one-way trip. Once a Pokémon leaves either game for HOME, it cannot return. 1
The permanent transfer rule
The Pokémon Company says Pokémon moved from FireRed or LeafGreen into Pokémon HOME can then travel to other compatible games, including Pokémon Champions. However, Pokémon from other games cannot be moved into FireRed or LeafGreen, so the two Game Boy Advance remakes remain isolated from incoming transfers. 1
That makes the new link more useful for preserving a collection outside the games than for moving a team back and forth. Anyone planning to restart either adventure should therefore decide carefully which Pokémon are leaving their original save before confirming a transfer.
Celebi is available without moving a team
The same update adds a Mythical Celebi gift in the mobile version of Pokémon HOME. Players can earn it by completing the FireRed and LeafGreen Pokédex, and Pokémon do not need to be transferred into HOME for their entries to count. Connecting the games is enough for registered Pokémon to appear in the HOME Pokédex. 1
Our opinion
The one-way rule is a serious caveat, but it is also the sort of detail that matters more than the headline compatibility announcement. Pokémon HOME works here as an escape route for a collection, not as a reversible storage box. The safest approach is to treat every transfer from FireRed or LeafGreen as permanent and use the Pokédex connection to claim Celebi without sacrificing a favourite team.
The feature is available through Pokémon HOME on Nintendo Switch, while the Celebi gift and Mystery Gift functions use the mobile app. 1