In these games, there is an address (D079 in Red/Blue, or D078 in Yellow) which changes the multiple of 10000 Pokédollars the player receives after defeating a Trainer. Since there is a cap of 9999 Pokédollars in the prize money calculation, this byte is not used for values more than 00, however, the game writes when the battle starts at 0E:5D07 to it when the battle starts. Like other money bytes, this address is defined so that the hexadecimal value in it is the same in decimal.
With arbitrary code executionThe following code for "8F" or "ws m" using a bootstrap code to item 3 code will set D079 or D078 to 99.
Item 3: Lemonade x 153
Item 4: TM34 x 121 (120 in Yellow)
Item 5: TM08 x 201