From BiSB's bonus round Opponent Watch:

Michigan has never played TCU. Michigan has, however played three purple teams in recent years: Northwestern, Washington, and Kansas State (you probably recall Michigan defeating both Northwestern and Washington last season). Michigan is a combined 67-21 all-time against those 3 teams for a combined win percentage of 76.1%.

This, of course, raises the obvious question: against what jersey color has Michigan had the most historical success? Based on some quick math, there appear to be three candidates: purple, black, and brown, all hovering around the 76% to 77% mark among teams Michigan has played at least four-ish times. Iowa, Purdue, Vanderbilt and Rutgers have done most of the heavy lifting for black, while Minnesota and Western Michigan have been responsible for most of Team Brown’s lack of success against the Maize & Blue. Grey has been the most successful against Michigan, although NOT RECENTLY FOR SOME REASON.

If anyone wants to take on that research task in the off-season, extra credit will be awarded.

So. It isn't the offseason yet, but what else are you gonna do? Watch the Gasparilla Bowl? No, that's insane. We need answers! Of course, BiSB has given us some answers above, but that's not the complete picture. You don't play football for over 140 years and just slap 3 B1G* teams and Vandy on black and call it good. No no no no, we need lots of data and a deep analysis (or at least whatever depth of analysis I can muster at the moment).

The good news is, the results are in: Michigan has the best record against purple teams. All-time winning percentage here is 79.31% which is almost 5% higher than any other color. Given BiSB's quick math skills, how is it so much higher? Well, he mentioned NW, UW, and KSU, but neglected some teams that put purple over the top. Here's the teams in purple and Michigan's records against them:

Albion: 16-1-0
Ann Arbor High: 1-0-0
Kansas State: 0-1-0
Kenyon: 1-0-0
Mount Union: 7-0-0
Northwestern: 59-15-2
Washington: 8-5-0

With only 7 schools in play here, the winning percentage is helped greatly from 16 wins against Albion and 7 over Mount Union. So there's your winner (or, I guess, loser). Congratulations, purple teams, you suck the most! But of course, that isn't the whole story here. After all, Michigan has 151 different opponents over the years and that's on 7 of them. No, we're just getting started with the data.

One caveat that will surely lead to wild arguments in the comments is what the hell to do with teams who have colors that are not really in a category. Not every team is just "purple and white" and call it good. In fact, from our winners (losers), Kansas State is technically royal purple and white. For every two-toned school with primary colors you also have your Delaware State's with their midnight blue and cherry red. There are many, many instances of this, and with all of them I've categorized colors according to their closest main color, which is often in the name anyway. Carnelian red and cherry red are obvious, but cardinal, crimson, and scarlet are also all just red. Additionally, some schools seek to distinguish their version of their color in a feeble attempt to make themselves seem far more important than they actually are. Carolina blue or Tech gold come to mind. The some of the worst offenders here are SMU and Penn, each with their own shades of red and blue. Of course, Penn is one of the oldest institutions in the country so they might actually have a claim to their shades. Regardless, it's all just red and blue. Here's the 10 colors I'm categorizing in:

black
blue
brown
gray
green
orange
purple
red
yellow
white

For these colors, I am using the colors I could find on a team's wikipedia page since it is a good source of consistent information (yes it is don't look at me like that Debbie!). Each color, regardless of its primary or secondary status, contributes to the data. For example, Penn State's record contributes to both blue and white. Maryland contributes to all 3 of red, gold, and black (and could technically also go to white, but I only went 3 colors deep here).

My biggest pain point was that I had the hardest time figuring out what to do with maroon and garnet. BiSB alluded to it in his OP, but maroon can either be red or brown. In my mind, it seems like it's pretty much always red. But I couldn't be subjective with it for the sake of the data, so everything had to go into one bucket or the other. Over the course of my research, I ended up siding with BiSB here and put all maroon and garnet teams under brown. If anything, there's a TON of red teams already, and only 3 teams that are truly brown: Bowling Green, Lehigh, and Western Michigan. If you think that skews the data, whatever.

Lastly, there's a number of teams I could not find a color for, despite exhaustive research. I'm not sure any of these would do much to the data even if I did have them, but they are there. Most of them are old athletic clubs or armed forces reserves. Aside from our 5-0-0 against Detroit Athletic Club and 2-0-1 against Michigan M.A, none of these schools have played us more than twice. In all, we are 25-5-1 against such teams.

With all of that out of the way, here's the raw data:

Adelbert 1-0-0 navy, white, gray
Adrian 1-0-0 black, gold
Air Force 3-0-0 red, silver
Akron 1-0-0 blue, gold
Alabama 2-3-0 crimson, white
Albion 16-1-0 purple, gold
American Medical 1-0-0 maroon, gold
Ann Arbor H.S 1-0-0 purple, white
Appalachian State 1-1-0 black, gold
Arizona 2-0-0 cardinal, navy
Arizona State 0-1-0 maroon, gold
Arkansas 1-0-0 cardinal, white
Army 5-5-0 black, gold, gray
Auburn 1-1-0 burnt orange, navy
Ball State 1-0-0 cardinal, white
Baylor 1-0-1 green, gold
Beloit 3-0-0 red, gold
Boston College 4-0-0 maroon, gold
Bowling Green 2-0-0 brown, orange
Brigham Young 1-1-0 blue, white
Buffalo 1-0-0 royal blue, white
Butler 1-0-0 blue, white
California 6-2-0 blue, gold
Camp Grant 1-0-0 n/a
Carlisle 1-0-0 red, white, gold
Carroll 1-0-0 orange, white
Case 26-0-1 navy, white, gray
Central Florida 1-0-0 black, gold
Central Michigan 4-0-0 maroon, gold
Chicago 19-7-0 maroon
Chicago A.A. 0-1-0 n/a
Chicago Athletic Club 0-1-0 n/a
Cincinnati 1-0-0 red, black
Cleveland A.A. 0-1-0 n/a
Colorado 4-1-0 black, gold, silver
Colorado State 2-0-0 green, gold
Columbia 3-0-0 blue, white
Connecticut 3-0-0 blue, white
Cornell 6-12-0 carnelian red, white
Dartmouth 1-0-0 green, white
Delaware State 1-0-0 midnight blue, cherry red
Denison 1-0-0 red, white
DePauw 3-0-0 black, gold
Detroit 1-0-0 red, white, blue
Detroit Athletic Club 5-0-0 n/a
Detroit Industrial 1-0-0 n/a
Drake 3-0-0 blue, white
Duke 6-0-0 duke blue, white
Eastern Michigan 10-0-0 green, white
Ferris State 1-0-0 crimson, gold
Florida 4-1-0 orange, blue
Florida State 1-2-0 garnet, gold
Georgia 1-2-0 red, black
Georgia Tech 1-0-0 tech gold, white
Grand Rapids 1-0-0 maize, blue
Great Lakes 2-0-0 n/a
Harvard 4-4-0 crimson, white, black
Harvard Club (Chicago) 1-0-0 n/a
Hawaii 4-0-0 green, black, white
Hillsdale 2-0-0 blue, white
Houston 3-0-0 scarlet, white
Illinois 72-23-2 orange, blue
Indiana 61-10-0 crimson, cream
Iowa 44-15-4 black, gold
Iowa Pre Flight 1-1-0 n/a
Kalamazoo 5-0-0 orange, black
Kansas 3-0-0 crimson, blue
Kansas State 0-1-0 royal purple, white
Kentucky 1-0-0 blue, white
Kenyon 1-0-0 purple, white
Lawrence 1-0-0 navy, white
Lehigh 1-0-0 brown, white
Long Beach State 1-0-0 black, gold
Marietta 2-0-0 navy blue, white
Marquette 2-0-0 blue, gold
Maryland 10-1-0 red, gold, black
Massachusetts 2-0-0 maroon, white
Memphis 1-0-0 blue, gray
Miami (Fla.) 1-1-0 orange, green, white
Miami (Ohio) 6-0-0 red, white
Michigan A.A. 2-0-0 n/a
Michigan M.A. 2-0-1 n/a
Michigan State 72-38-5 green, white
Middle Tennessee State 1-0-0 royal blue, white
Minnesota 77-25-3 maroon, gold
Mississippi 1-0-0 cardinal, navy blue
Mississippi State 0-1-0 maroon, white
Missouri 2-2-0 old gold, black
Mount Union 7-0-0 purple, white
Navy 12-5-1 navy blue, gold
Nebraska 7-4-1 scarlet, cream
North Carolina 1-2-0 carolina blue, white
North Carolina State 1-0-0 red, white
Northern Illinois 2-0-0 cardinal, black
Northwestern 59-15-2 purple, white
Notre Dame 25-18-1 blue, gold
Oberlin 9-0-0 red, gold
Ohio Northern 3-0-0 orange, black, white
Ohio State 60-52-6 scarlet, gray
Ohio Wesleyan 2-1-1 red, black
Oklahoma 0-1-0 crimson, cream
Oklahoma State 2-0-0 orange, black
Olivet 2-0-0 red, white
Oregon 3-2-0 green, yellow
Oregon State 5-0-0 orange, black
P&S Chicago 2-0-0 n/a
Peninsulars 1-0-0 n/a
Penn State 16-10-0 blue, white
Pennsylvania 11-8-2 penn red, penn blue
Pittsburgh 2-0-0 blue, gold
Princeton 2-1-0 black, orange
Purdue 46-14-0 old gold, black
Quantico Marines 1-0-0 n/a
Racine 1-0-0 n/a
Rice 2-0-0 rice blue, rice gray
Rush Lake Forest 2-0-0 red, black
Rutgers 7-1-0 scarlet
San Diego State 2-0-0 scarlet, black
South Carolina 1-3-0 garnet, black
South Dakota 1-0-0 coyote red, white
Southern California 4-6-0 cardinal, gold
Southern Methodist 2-0-0 SMU red, SMU blue
Stanford 6-3-1 cardinal, white
Stevens Institute 1-0-0 stevens red, gray
Syracuse 6-5-1 orange
Tennessee 0-1-0 orange, white
Texas 0-1-0 burnt orange, white
Texas A&M 2-1-0 aggie maroon, white
Toledo 0-1-0 midnight blue, gold
Toronto 1-0-1 blue, white
Tulane 3-0-0 olive green, sky blue
U. Club (Chicago) 1-1-0 n/a
UCLA 8-3-0 blue, gold
UNLV 1-0-0 scarlet, gray
Utah 1-3-0 red, white
Vanderbilt 10-0-1 black, gold
Virginia 3-0-0 orange, blue
Virginia Tech 1-0-0 chicago maroon, burnt orange
Wabash 1-0-0 wabash scarlet
Wake Forest 2-0-0 old gold, black
Washington 8-5-0 purple, gold
Washington State 4-0-0 crimson, gray
Washington Univ. (Mo.) 1-0-0 red, green
Wesleyan 0-1-0 cardinal, black
West Virginia 1-0-0 old gold, blue
Western Michigan 8-0-0 brown, gold
Western Reserve 2-0-0 n/a
Windsor Club 2-0-0 n/a
Wisconsin 52-17-1 cardinal, white
Wittenberg 2-0-0 red, white
Yale 2-2-0 yale blue

In total, here's Michigan's record and winning % against each color, with teams of consequence listed:

1. Purple: 92-22-2, 79.31% (Northwestern, Albion, Washington, Mt. Union)
2. Orange: 108-34-3, 74.48% (Illinois, Syracuse, Kalamazoo, Oregon St, Florida)
3. Black: 166-51-6, 74.43% (Purdue, Iowa, Maryland, Vanderbilt, Army, Colorado)
4. White: 395-129-12, 73.69% (Michigan State, Indiana, Northwestern, Wisconsin, Case)
5. Brown: 123-40-4, 73.65% (Minnesota, Chicago, Western Michigan. Boston College)
6. Blue: 237-77-8, 73.60% (Illinois, Case, Notre Dame, Penn State, Navy, Penn, UCLA)
7. Yellow: 332-110-11, 73.29% (Minnesota, Purdue, Iowa, Notre Dame, Albion, Navy)
8. T-Red: 294-139-12, 67.59% (Indiana, Ohio State, Wisconsin, Penn, Maryland, Oberlin)
9. T-Green: 98-41-6, 67.59% (Michigan State, Eastern Michigan, Hawaii, Oregon, Tulane)
10. Gray: 108-58-7, 62.43% (Ohio State, Case, Army, Colorado, Washington State)

I went by winning percentage here since going by straight number or wins or loses is highly dependent on the number of teams instead of how Michigan actually did against those teams. Still, interesting that white, yellow, and red have the most games played against them. Purple has the least, but is not far from the clump of orange, green (which are tied at 145 games apiece), brown, and gray.

No surprise that historical B1G teams dominate important teams here, but old school games against teams like Case (26-0-1), Notre Dame (25-18-1), Chicago (19-7-0), Albion (16-1-0), Navy (12-5-1), Penn (11-8-2), Oberlin (9-0-0), and (damn you!) Cornell (6-12-0) all contribute heavily to these totals.

As far as things we've learned, I have a few ideas: If we ever end up playing the likes of LSU or Clemson, historical precedent is heavily favoring Michigan. Those purple teams better watch out! Clemson, particularly, has a double whammy with both purple and orange. I'm sure we'll be happy to add them to the carnage. Secondly, I'm unsurprised, but it's always great to see that we just own all of college football (except for freaking Cornell... ugh). At worst we still have a 62.43% winning percentage, which is much better than most schools can say. I'm thankful that researching a topic like this was not full of pain and suffering and instead was a joy for the most part. Thank you, BiSB for the inspiration!