I have a spreadsheet of data that was taken as an extract. It's basically got a load of different organisations on and their status at certain periods time.
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Use a pivot table or a column with COUNTIFS to show how many dates that company has not had this status, you can then filter on that column.
Limitation of this is when an item reverts back to a status that it has previously had. eg Lge 1, Lg2, Lge 1 again. There will be the same limitation using the pivot method.
Below the calc in D2 =COUNTIF(A:A,A2)-COUNTIFS(A:A,A2,B:B,B2)
Or a bit more complicated, the next column E indicates when there was a change in status. See Portsmouth has a 1 where they were relegated.
This assumes the data is in chronological order. It is checking if the next sequential row for this team has the same or different status.
Team and status do not need to be sequential, I added Liverpool within Portsmouth data to demo.
calc in E2 =IF( IFERROR( OFFSET($B$1, MATCH(A2,A3:A9999, 0)+ROW(A2)-1, 0 ), B2 ) =B2, 0,1 )
copy that down the column
Note I have only done the match to row 9,999. You can also calc that bit up using INDIRECT function, but it becomes less readable.