Sudoku Puzzle Master

Xiao Ming looked down at his 9 sudoku puzzles, each a plastic grid with interlocking edges. He smiled in anticipation, waiting. Shamus, the Irish sudoku master, gleefully rubbed his hands together as he waited for the ring of the bell.

"Ting!" went the bell, and they each reached for a their spinners. Xiao Ming flicked and the needle went round and round till it landed on a 6. Spotted a small place, grabbed a '6' tile, and slotted it into the sudoku board. 'Flick' again, a '7'.

Shamus, on the other hand, had a problem. His spinner had landed on a '9', and he didn't know where he could slot it. He put it into the slot queue, and waited for the penalty timer to run out. "It's not fair," he complained, "Me spinner dont go round and round, it go square and square!" Finally his penalty timer ran out, and he got to spin again, this time, a '3', which was an easy place, this time.

--A bit later--

Xiao Ming's 9 sudoku's were almost finished. Just a few more numbers to slot. There! Xiao stuck the last '8' into place, and grabbed the nine completed sudokus. The Aisa Grand Sudoku Master slotted the interlocking edges together and turned it over, to form the grand sudoku, the final sudoku, with one number per 3x3 grid-square on the other side..

The last challenge...