There is no key it opens when you become a Pokemon champion.
the basement
select
Watson gives it to you
where you use the key to turn on the quary.
To get to new mauville
say thank you
As far as I know there is no code for key items.
Ruby & Sapphire Key
go to route 127 and 128,then go underwater.
No they are not, braille and the unown are two different alphabet systems.
Find the key at a under water cave
Maybe your Pokemon is holding a key item, or your Pokemon might know a hm move or your game might be messed up