The Japanese version of Transformers: Beast Wars Metals 64 is Transfer Pak compatible with Kettou Transformers Beast Wars: Beast Senshi Saikyou Ketteisen, another Japan-exclusive Gameboy Color counterpart. When connected, the Megatron X skin becomes unlocked.
Also, if any other GB cart is inserted upon boot up, a bonus perk might be awarded to the player such as a bigger health gauge.
This was released in America but since the GBC game never came stateside, the Transfer Pak feature was removed altogether. However, thanks to the dedicated modding community, Megatron X can be patched into the US version.
