I think with this post I'll record my findings and edit it if something comes up. Currently doing King Ghidorah's fireball feedback. I think in time it won't matter regarding projectile strength as opposed to making some sort of chart specifically for Super Mechagodzillla's plasma grenade feedback.
Air weak version, 1 gives 2, 2 gives 3, 3 gives 4.
Air strong version 1 gives 2, 2 gives 3, 3 gives 4, gives 5.
Ground weak version, 1 unit gives 2, 2 gives 4, 3 gives 6.
Ground strong beam 1 gives 2, 2 gives 4, 3 gives 6 and 4 gives 7.
Breath is hard to know. 1 small breath gives 2-10 or 2-16 from the stronger one
Rage ... 14 from the five units. This is probably the fastest fireball in the game. 4 for 13. This is a very special fireball because it breaks the beam cancel beam rule, which goes to show certain projectiles have hidden properties.
Air lightning weak strength offers one unit per unit so no weird inconsistencies at least for the weak strength. Once you use the strong version the first lightning unit gives 2 as opposed to 1. 2 gives 3 plasma units, 3 gives 4, and the full absorption of 4 gives 5 back.
On the ground 1 segment of a weak bolt offers 2. 2 offers 3 and 3 offers 5. For strong bolts, 1 segment gives 2, 2 is unknown, 3 gives 6 and 4 gives 7 (wow).
For the rage, landing it closer does more hits and can even do full stun if you catch opponents near the mouth in the air. However, the absorption remains the same at a solid 16.
This guys beams don't offer much because he's meant to fight up close.
Air weak beam 1 gives 2, 2 gives 3, 3 gives 4. Air strong is 1 gives 1-2, 2 gives 2, 3 gives 3, 4 gives 3-4 but mostly 4.
Ground weak beam is 1 gives 2, 2 gives 3, 3 gives 5. Strong ground beam is 1 gives 1, 2 gives 2-3 mostly 2, 3 gives 3-4, 4 gives 4-5.
Flamethrower is too difficult to know. You can give 1-5 with weak version or up to 16 for the strong version.
Air bolts give 3 or 4 and back. Can't think of a way to separate the segments but no biggy.
Ground bolts weak version 1 segment gives 2 back, 2 for 3 and 3 for 5. Strong beam is the same except 4 gives 6.
Weak napalm bomb can give 1-4 while strong version can give 2-6. Random trivia, it seems it can plow through Gigan's beams so they're actually weak projectiles?
Rage bomb .... 5-15 from what I could land. Once again it should be noted the pillars of fire are what can be absorbed.
Air weak eye beam 1 segment gives 2, 2 gives 3, 3 gives 4. Strong is 1 gives 2, 2 gives 3, 3 for 4, 4 for 5.
Ground beam weak 1 gives 2, 2 for 3, 3 for 4. Strong is the same except 4 gives 5.
Ground volt is too hard to separate and comes out in either 5 or 8 segments returned with 4 or 6 from the plasma grenade.
Flamethrower weak gives 1-6 while strong gives 1-13.
Supermechagodzilla can absorb the falling rockets from flight mode but he won't be able to shoot anything back
These rockets don't damage and can build meter as well as stun like crazy.
Weak beam is 1 gives 2, 2 for 3, 3 for 4. The strong 4 beam gives 5.
Dust can give anywhere from 2 to 10 I think.
Air beam 1 segment offers 4 while strong gives 5.
Ground weak 1 segment gives 2, 2 gives 4, 3 gives 6 like Godzilla. Strong gives 7 back.
Laser eye weak shoots 5 while strong shoots 10. The feedback is 4 and 8.
Smoke gives 8, small lasers give one a piece, cannon in long mode gives 2 while sentry mode cannon gives 3.
Phew, all done for the energy work, now we need a chart. I wonder what his maximum charge is? One last note. And this might apply to everyone with segmented "beam" type projectiles. Super Mechagodzilla's strong beam (4 segments) can be negated by Godzilla's weak beam (3 segment) but ONLY when it's done late.
Last play I went and checked on some bubbling questions I had. For Gouten, you can reset his meter by stunning him beneath ground level but he just won't have his rage ready. Both Gouten and Godzilla have weird fireballs, namely Godzilla's rage. They don't act the way they're suppose to in terms of cancelling. An example would be Biollante's rage attack. It mows through fireballs and is considered a moving grab much like rush type moves. It breaks Godzilla's breath EXCEPT his rage version. It moves right through regardless. The same principle doesn't apply to either Gigan or Mothra's rush moves, they destroy fireballs. Speaking of rush moves, the only one I have seen consistently interrupt it is Megalon's drill dash. Everything else gets tagged unless it's done early before the rush begins. One final observation relates to Super Mechagodzilla's G crusher once again. It moves through energy but not acid and not missiles unlike Gigan and Mothra.