I was able to change both of the following using gameboy assembly editor and goldfinger :)
Shiny Encounter Rate 1/254
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offset 0x9052
ld l,c ; 69
ld h,b ; 60
ld a,[hli] ; 2A
and a,$CC ; E6 CC
cp $CC ; FE CC
jr nz,+$09 ; 20 09
ld a,[hl] ; 7E...