Here are my findings on damage scaling in MvCi. Let's hope this info proves useful in optimizing your combos.
In MvC3 each strength button had a different minimum scaling. **That is not the case in MvCi**. Instead, the entire damage scaling is determined entirely by ONLY the first hit
. Take this Thor combo I found on Youtube.
First off, hats off to Capcom for normalizing the damage on single hit normals so this was easier to test. Thor's HP is 800 no matter if it's standing, crouching, df+HP or jumping. Same with HK. This is important because I rerecorded the combo but instead of starting with an AD j.HP I started with a c.LK (200 damage less starter).
Instead of the df+HP into launch later on, I did s.HK for the same base damage. But... what? The combo does 500 damage less. Not 200. So analyze this hit by hit.
Heavy starter: scaling goes 100, 90, 80, 70, 60, 50, 40...
Light starer: scaling goes 100, 81, 72, 63, 54, 48, 45... wait what?
The conclusion? Starting the combo with a light is easier
so the engine punishes you by scaling the combo worse
Projectiles seem to make the scaling be a little odd. If you hit with a projectile and convert with a light, two attacks will have the same scaling, then the scaling will proceed as a heavy starter would.
Note in that video that the two HPs in the air deal the same damage so they're in the same damage scaling.
Throws scale the followup hits to start at 30%-30%-25%-etc. but the combo scales like heavy starter past that. Hitstun deterioration by then is large but you can OTG, launch and two heavies no problem.
Command throws, though I only attempted Thor's and it does huge damage which is known to also affect hitstun scaling, starts the followups at 25%, which means heavy starter-type scaling as well. Hitstun deterioration is so bad you can't combo two heavies in the air after OTG and launch.
Multihit moves will advance the scaling every 2 hits. For example, Thor's 3-hit air qcf+LP will have the first two hits do the same damage, then the third hit will be the next number. Inserting f+HP (1 hit) before launcher does not scale the launcher but DOES add a hit (so scaling can do something like 100, 90 (f+HP), 90 (launcher), 70 (even though the launcher damage was scaled higher it counted anyways, etc.). There needs to be a little more investigation which is why I'm putting it out there.
Notes on Character Health
Seems as though scaling also occurs on low health a little differently, but this needs investigating. This isn't unusual for a Capcom game. The original Thor combo listed does 8k to characters 10k or highter health, but only 7.8k to 9k-health characters.
Q1: So what's optimal?
Honestly, if you're concerned with the best damage you can get the optimal way to go is to mix the opponent up until you connect with a heavy. We all know that's not exactly the easiest way to open an opponent up, although remember that sweeps and some low command heavies can link into launch. Additionally, some characters can instant air dash into heavies with great hitboxes that can cross up, and Soul Stone can set up some cross up oki situations, so starting a combo with a heavy is not as rare as we might initially think.
Q2: Is it optimal then to use multihit cancellable normals like Thor's f+HP for 1 hit every single time you can, since they don't move scaling for the next hit?
This one is a bit trickier. Scaling does move along, one step even though the number doesn't show it (so f+HP 1 hit into launch doesn't scale the launcher any more than just launching, but the next thing after the launcher is scaled 1 more hit). The problem I found was the increase in hitstun deterioration, at least in the route of the Thor combo I show in this post. It's possible, but the window to rejump jHP is much shorter, almost prohibitively shorter. I suppose it's a case by case basis.
Q3: You mention projectiles changing the scaling. Can you explain that in more detail?
LOL no, I cannot. There has to be a pattern and I can't see it. Although at least for Thor a j.HP dash canceled into j.HP makes the second one not scale and then the scaling is reset to a heavy starter scaling, not every character has an air dash. So if anyone can see the pattern, please post it here.