GBA Project [Release] Celio-Link – Online Battle, Trade, and Record Mixing for Gen 3 Pokémon Games

Essometer · Feb 28, 2026

Hello,

today, I'd like to show you the actual release of Celio-Link. It allows you to trade, battle and record mix Generation 3 Pokémon Games online.

All you need to connect is a USB to GBA Link adapter and an original Nintendo GBA Link Cable.
Some repoduction ones work as well, but they need to have the GND pin populated.

Supported Games:

Pokémon Ruby
Pokémon Sapphire
Pokémon FireRed
Pokémon LeafGreen
Pokémon Emerald

Supported Modes:

Online Trading
Online Battles
Online Record Mixing
Online Contests (Emerald only)
Online Battle Tower Double Battle (Emerald only)
Works with original, unmodified hardware
Built-in Trade Emulator (no second console required)

Here is a video of how it works in action.

You can visit the client under https://celi0.link

The firmware can be found under releases in my github repo https://github.com/Celio-Link/Celio-Firmware

This is also where you find links to the PCB and a shop that sells them already assembled.

You can also use it to trade solo using the trade emulation.

Here are some picture of my current PCB setup

This is how the GBA cable connector needs to look like. Cheap cables only have 4
contacts in them while better one will have 5. You need one with 5 contacts.

Flame · Feb 28, 2026

Pokémon? Gen 3? Online? Only thing missing is hookers and blow.

nice.

fmhugo · Feb 28, 2026

Technology is incredible.

Essometer · Feb 28, 2026

I do what Nintendon‘t.

Starlark · Feb 28, 2026

One note from the adapter pics. When not using level shifters be careful not to bridge VCC 5v supply of the pico to its 3.3v as this could cause damage overtime so make sure the switch is in the GBA position for anyone else wanting to DIY a cable. Could also remove this VCC jumper cable completely to be safe.

This project is incredible thank you for your work. I have done a number of trading and battling including double battles and once a battle or trade starts I have had no desyncs or dropouts yet. I can get a desync if running around in the room for a while but that is to be expected. Actual trade/battle logic has been incredibly stable. Awesome work.

I am working on a new solderless version of the board that supports gen3 with GBC cable and can trade pokemon gen1-3 as well as gameboy Tetris online play and can send multiboot files to gba as well as a printer emulator and soon Dr. Mario support.

New board has software controlled voltage switching between 5v GB and 3.3v GBA modes. Hoping to merge my firmware functionality into your version to make the firmware client agnostic. If anyone wants to follow along the collection of projects can be found at https://gblink.io

druidsareus · Mar 1, 2026

Would the analogue pocket gba cable work?

Starlark · Mar 1, 2026

druidsareus said:
Would the analogue pocket gba cable work?

I'm curious how that cable switches between GBC and GBA modes but if it has a ground and can be used as a GBA cavle it should work

Kwyjor · Mar 1, 2026

Starlark said:
New board has software controlled voltage switching between 5v GB and 3.3v GBA modes.

So, will these boards work with https://github.com/Lorenzooone/gba-dump-gb ?

It has always struck me as a very intriguing project, but the lack of documentation for the USB link cable adapter seems to limit its utility. If those adapters become more widely available, it could make dumping GB/GBC carts much easier.

druidsareus · Mar 1, 2026

Starlark said:
I'm curious how that cable switches between GBC and GBA modes but if it has a ground and can be used as a GBA cavle it should work

It has 6 contacts and a switch to change from gba to gb/c as you can see in the pictures I took. So I think it would work? I bought the complete version of the gb-link from moderngameboy on Etsy so I guess in a week or two we will know for sure lol

Essometer · Mar 1, 2026

Kwyjor said:
So, will these boards work with https://github.com/Lorenzooone/gba-dump-gb ?

It has always struck me as a very intriguing project, but the lack of documentation for the USB link cable adapter seems to limit its utility. If those adapters become more widely available, it could make dumping GB/GBC carts much easier.

Yes, it should be the same board, you can flash it.

druidsareus said:
It has 6 contacts and a switch to change from gba to gb/c as you can see in the pictures I took. So I think it would work? I bought the complete version of the gb-link from moderngameboy on Etsy so I guess in a week or two we will know for sure lol

I think that should work fine.

Here is a seller that sell the PCB or the complete adapter

https://www.etsy.com/de/listing/1517956485/gb-link-usb-zu-gameboy-link-adapter-fur

Starlark · Mar 1, 2026

Kwyjor said:
So, will these boards work with https://github.com/Lorenzooone/gba-dump-gb ?

It has always struck me as a very intriguing project, but the lack of documentation for the USB link cable adapter seems to limit its utility. If those adapters become more widely available, it could make dumping GB/GBC carts much easier.

Yes that would also be for the same adapter.

Wokann · Mar 3, 2026

It's amazing. can it work for other gba games?

Essometer · Mar 3, 2026

Yes and no, currently depends on the GBA Game. My focus was Pokémon because I was very familiar with the Games and
it is probably the number one use case.

This version has some parts in it that will make it only work the Pokemon in the current from, my guess is that while it can not be completly game agnostic, it would be possible to support more games. It just has to be on a game to game basis.

Warmo · Mar 3, 2026

Gonna keep a eye on this, looks interesting ^^
I built a arduino gb printer board that other year so would make a neat project

Quick question, on your pictures, why have u used wires to jump the connectors instead of using the “logic level converter” on the GitHub link?

Essometer · Mar 3, 2026

Warmo said:
Quick question, on your pictures, why have u used wires to jump the connectors instead of using the “logic level converter” on the GitHub link?

I only needed the GBA functionality of the board since I am not really interested in GB(C) development. The logic converter converts to 5V, but the RP is 3.3V natively, so I just jumped the pins.

Just laziness on my part.

Trip_Away · Mar 20, 2026

Me: Oh nice! A way to trade pokemon in Gen 3 between internet to complete my Pokedex and mix records and all in original console!
*You need a device that is sold out and the another options needs soldering. Also, you had to pay a extra $25 dollars fee for shipping to my country*
Me: Buck my life.

Essometer · Mar 20, 2026

To be fair, the soldering is very beginner friendly and the pcb and controller are dirt cheap. If you ever wanted to learn so soldering, this is a perfect project to start

Sekii · Mar 21, 2026

Reminds me of another project that needed you to connect a GBA to a Wii via GCN-GBA Link Cable to play online. While certainly impressive, it unfortunately required an Emerald rom hack.
This solution being compatible with the actual cartridges is very nice.

Trip_Away · Mar 26, 2026

Sekii said:
Reminds me of another project that needed you to connect a GBA to a Wii via GCN-GBA Link Cable to play online. While certainly impressive, it unfortunately required an Emerald rom hack.
This solution being compatible with the actual cartridges is very nice.

Which proyect was that? And which Emerald rom hack needs?

Essometer · Mar 26, 2026

Trip_Away said:
Which proyect was that? And which Emerald rom hack needs?

They are refering to this
https://github.com/KittyPBoxx/pokeemerald-net-demo

GBA Project [Release] Celio-Link – Online Battle, Trade, and Record Mixing for Gen 3 Pokémon Games

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