Use nested MATCH within IFERROR, e.g.
=IFERROR(MATCH(A1,Sheet1!A1:A100,0),IFERROR(MATCH(A1,Sheet2!A1:A100,0),IFERROR(MATCH(A1,Sheet3!A1:A100,0),... etc )))
Return index if A1 is found in Sheet1, if not
return index if A1 is found in Sheet2, if not
return index if A1 is found in Sheet3, ...etc