Is it the game with more supported peripherals of all time?
Let's look at how many peripherals Crystal can connect to:
>Link Cable
>Super Game Boy (with some hardware tricks)
>Game Boy Printer
>Game Boy Camera
>N64 Transfer Pak
>Pikachu 2 GS
>Mobile Adapter GB
>Game Boy Player

You can also play on these systems without any accessory needed:
>Game Boy Color
>Game Boy Advance
>Game Boy Avance SP

And finally, the games it can communicate with are:
>Red
>Green
>Blue
>Yellow
>Gold
>Silver
>Stadium
>Stadium 2
>Mobile Trainer

No other game has this much connectivity…