This is difficult to do, but possible if you allow yourself to compromise the image quality of all the cameras to the camera with the worst image quality.

For some events I shoot with 3 cameras (multi cam). At the moment that's 2x GH2 and 1x GH4. (GH4 is used as the A cam, or where a 4k image is an advantage for reframing.

I intercut the GH4 with my hacked GH2 (Sanity 5.1). Gh2 std profile with everything but saturation dialed down. Gh4 CinelikeD everything but saturation dialed down. I use cinelike D in case I need the softer contrast it affords, otherwise I would use the std profile.

I use manual white balance, usually 3200k or 5600k. I only go into the green/Magenta offset, if I feel it needs it. I am religious about making sure both cameras have the same settings.

Then in premiere I create a color correction filter for each. For the Gh2 I soften the contrast a bit. For theGH4, I add contrast to the shot. Color I can pretty much leave alone unless the Gh4 is slightly different than the Gh2 image.

I then lay these filters on a multi cam clip from all 3 cameras and start judging & tweaking. Once I am happy, I lay the filters on all the clips and start editing. When I am done editing, if some shots "fall out" from the others I go back and adjust the CC filter again, just for those clips, saving the old one and creating a new one for the reworked filter.

-I will add, I do this usually indoors under controlled lighting, so things don't change much. I try to keep the same ASA and f-stop on each camera (I use manual lenses with f stop ring, mostly all from the same manufacturer: Nikon)

You could test this in advance with all your cams rolling at the same time, with a color and resolution chart in the frame (same size in each frame). Then do this process above. You may find the different sensors & lens combos have trouble being matched, or that one cam is simply too far off from the others to use.

Doing this in advance will save you tons of headaches in post, but you must be religious about keeping setting like color temp, ASA, F-stop the same across all cameras (if they even match between manufacturer). This is a bit easier for me since all my cameras are from Panasonic and share the same color science and some other tidbits (but different sensors)

If it's all too much then KISS (keep it simple, stupid). Shoot with only your best camera, or best camera for the scene.

5D note: I once had to color correct a film shot with a 5Dmkii super flat with a Sony HD handy cam (small sensor). The 5dmkii was really soft and colors were flat, the Sony handy cam, wicked over-sharp and saturated. After pumping up the 5dmkii footage to just under it's breaking point, all the Sony footage had to be softened and desaturated (degraded) to match the 5dmkii's look. The film was passable and that was the best "look" it could ever have. The director/producer was so happy, I had "fixed" his film. his DP was supposed to be a genius, lol.

Choose your path wisely, since you might not be able to give the film a creative look, just a technical grade to make it all look passable. If I were you, I'd forget about the 5dmkii (soft & moire prone) unless it's the only cam used in a scene and you want that ultra shallow dof or low light capability, and just use it for that scene. Don't just cut it in with the other cameras and think you can sort it out magically in FCPX with the auto shot matching CC button (it doesn't work well, to say the least) or some other software. Or shoot ML RAW on the 5Dmkii and some of the issues I had will be gone. I don't have experience with DJI footage.

Try out these settings for the GH4/GH2 combo. +1 on the Flowmotion 2.02 firmware. I prefer the GH2 Smooth setting and GH4 Natural settings below.

GH2= Smooth -2 -2 -2 -2

GH4=Natural=16-235:

• Contrast=0
• Sharpness-3
• Noise Reduction-5
• Saturation-1
• Hue-0

GH2= Cinema -2 -2 -2 -2

GH4=Cine D=16-235:

• Contrast=0
• Sharpness-3
• Noise Reduction-5
• Saturation-2
• Hue-0

GH2= Smooth -2 -2 -2 -2

GH4=Cine V=16-235:

• Contrast=0
• Sharpness-3
• Noise Reduction-5
• Saturation-3
• Hue+1
• iDynamic=Standard
• iResolution=Standard
• Master Pedestal+7