I am assuming your dates are in Column A starting from A2 :
=TEXT(
IF(LEN(A2)=8,
DATE(MID(A2,5,4), MID(A2,3,2), LEFT(A2,2)),
IF(LEN(A2)=10,
DATEVALUE(SUBSTITUTE(A2,".","/")),
IF(LEN(A2)=9,
DATEVALUE(SUBSTITUTE(A2,"-","/")),
IF(LEN(A2)=6,
DATE(2000+RIGHT(A2,2),MID(A2,4,2),LEFT(A2,2)),
DATEVALUE(A2)
)
)
)
),
"dd.mm.yyyy"
)
If you want the solution in ADF please tell me :)