Looks like you're in luck json. Robo gets the third GFX pack pointer in the ROM, which yields an address of 0x147C40. Rusty Robo gets the 223rd GFX pack pointer for an address of 0x1FF913.
Check
here for other sprite info and let me know if you find any mistakes in the lists so I can fix those. The sprite header order should correspond with what's in Chrono Tweaker.