The precious Pokemon we spent hours capturing in the early nineties remain trapped, not just by pokeballs, but within a cartridge ravaged by time. Generally, Pokemon games before the GameBoy Advance era had SRAM and a small coin cell to save state as NVRAM (Non-volatile random access memory) was more expensive. These coin cells last 10-15 years, and many of the Pokemon games came out 20 years ago.  decided to ditch the battery and swap the SRAM for a proper NVRAM on a Pokemon Yellow cartridge, 23 years later.
The magic that makes it work is a FRAM (ferroelectric random access memory) made by Cypress that is pin-compatible with the 256K SRAM (made by SK Hynix) on the original game cartridge PCB. While FRAM data will only last 10 years, it is a write-after-read process so as long as you load your save file every 10 years, you can keep your Pokemon going for decades. For stability,  added a 10k pull-up on the inverted CE (chip enable) pin to make sure the FRAM is disabled when not in use. A quick test shows it works beautifully. Overall, a clever and easy to have to preserve your Pokemon properly.
Since you’re replacing the chip, you will lose the data if you haven’t already. Perhaps you can use [Selim’s] Pokemon Transporter to transport your pokemon safely from the SRAM to the FRAM.