Mad Matrix Hero: Use the Heal Cannon on the robots and use CC in the green tower to skip the long platform rides.
Hmm... I might try that later.
edit: Redid, and under 6 minutes (5:57.89). I used CC, but I got hit a few times. Also, I think exiting the red tower is slower than getting it last.
Iron Jungle Dark: When you use CC, make sure that your mission character is Eggman; that way CC will take you to the upper route, instead of to the lower route with the long rail. (Actually, it might also work with no mission character; I forgot where CC takes you in that case.)
Space Gadget Dark: I believe I got the blue light and used CC with Doom's Eye as my mission character (so I'd go down the Dark path). Though I'm guessing that wouldn't account for all that time--this level in particular can take a lot of practice to get good at.
Oh, so that's
why a lot of my CCs on the Hero misson went on the Dark path. I'm guessing that getting the 2nd defense unit first then the blue light is the best way, since I did the opposite several times and the S. Rifle shots always missed the unit.
Lost Impact Hero: Not sure about this one, but I think I used CC to skip all or part of a gunlift ride.
In an attempt earlier, I used it partway through the lift right before the area with the meteors, but screwed up somewhere, and got a lower time, but I get the idea.
Thanks for the help. I'll give a few of them a try.