Need Some Help

There's a few things to consider, I think I got them all removed in code below. Download xkas, copy the content of the code block below in a text file and rename the file "sketch.asm", edit the spell ID at beginning of file, save the file in same folder as xkas. Make sure your ROM has no header and use windows command prompt to type:

xkas sketch.asm romname.smc

I tested the compilation so the ASM file is good but I'm not sure if it will be bug or crash free in-game. You can go look in banks $C2 and search "sketch" and you will find the place of each org instruction (which go on an offset and write the new code). I find working with an assemebler a lot better than dealing with a hex editor and hex commands, it's a better practice in general unless you edit 1 or 2 bytes..

Edit: I added optional stuff for Control but for now it will no be executed unless you uncomment the code.

Code:

hirom

!sketch_spell    = #$00      ;change for whatever spell ID in hexadecimal, like 00 is Fire here

;-------------------------------------------------------------------------------
; sketch
;-------------------------------------------------------------------------------
org $C2151F
    LDA !sketch_spell   ; load sketch spell
    JMP $1712

org $C23E77
dw $388C                ; point sketch special effect to RTS

org $C25454
dw $00                  ; remove Sketch as command to be replaced by another one (Control)
                        ; this just set entry as being Fight command which is already there
                        
org $C22C21
BRA .continueA          ; skip sketcher check

org $C22C28
.continueA

org $C231EC
BRA .continueB          ; skip sketcher check

org $C231F2
.continueB

;-------------------------------------------------------------------------------
; Control
;-------------------------------------------------------------------------------
; remove ";" from the beginning of the two line below to enable
;org $C23E73
;dw $388C               ; point control special effect to RTS

; remove ";" from the beginning of the two line below to enable
;org $C25459
;dw $16                 ; remove Control as command to be replaced by another one (Sketch)
                        ; this just set entry as being Jump command which is already there