Since 1968 through 2015 there has never been a year when the champion from every classification all finished undefeated in the same year.
Here are the close ones.
1970
C1 12-0 Cass Midway
C2 12-0 South Shelby
C3 11-0 Chillicothe
C4 11-1 SLUH
1971
C1 10-0 Tarkio
C2 12-0 Monett
C3 11-1 Richmond
C4 11-0 Rockhurst
1976
C1 13-0 Cass Midway
C2 12-0 Lexington
C3 12-1 Memorial Jolpin
C4 13-0 Jefferson City
2000
8-man 12-0 Wirth County
C1 14-0 Santa Fe
C2 12-1 St. Pius X KC
C3 14-0 Platte County
C4 14-0 Webb City
C5 14-0 Rockhurst
2003
8-man 11-0 Mound City
C1 14-0 Marionville
C2 14-0 Centralia
C3 14-0 Harrisonville
C4 14-0 Kearney
C5 12-1 Park Hill
C6 13-0 Blue Springs
2007
8-man 12-0 Worth County
C1 14-0 Orrick
C2 14-0 Lawson
C3 14-0 Harrisonville
C4 14-0 Lee's Summit West
C5 12-1 Waynesville
C6 13-0 Rockhurst
Here are the close ones.
1970
C1 12-0 Cass Midway
C2 12-0 South Shelby
C3 11-0 Chillicothe
C4 11-1 SLUH
1971
C1 10-0 Tarkio
C2 12-0 Monett
C3 11-1 Richmond
C4 11-0 Rockhurst
1976
C1 13-0 Cass Midway
C2 12-0 Lexington
C3 12-1 Memorial Jolpin
C4 13-0 Jefferson City
2000
8-man 12-0 Wirth County
C1 14-0 Santa Fe
C2 12-1 St. Pius X KC
C3 14-0 Platte County
C4 14-0 Webb City
C5 14-0 Rockhurst
2003
8-man 11-0 Mound City
C1 14-0 Marionville
C2 14-0 Centralia
C3 14-0 Harrisonville
C4 14-0 Kearney
C5 12-1 Park Hill
C6 13-0 Blue Springs
2007
8-man 12-0 Worth County
C1 14-0 Orrick
C2 14-0 Lawson
C3 14-0 Harrisonville
C4 14-0 Lee's Summit West
C5 12-1 Waynesville
C6 13-0 Rockhurst