Ok time for a wishlist.
System Changes
-One TAC-counter input lasts for entire combo or until TAC’ed against. This prevents ‘resetting yourself’ by mashing TAC-counter only for your opponent to drop their combo and get a free new combo while you whiff j.:s:
-Greatly reduced XF2/3 timers: XF3 should last 8 Marvel seconds maximum.
-If you get hit after calling an assist but before it becomes active the assist character just leaves after a brief period of vulnerability (similar to Dark Harmonizer vulnerable duration).
-Getting hit / blocking chip damage during your own combo (e.g. by Viewtiful Joe’s Shocking Pink) does not reset your assist availability for that combo.
-Hard tags do not hit overhead.
Pipe-dream change: Completely remove rock-paper-scissors bullshit TAC system. Replace with TvC TAC system but keep the unscaled hitstun on post-TAC combos until you land.
Character changes:
Akuma:
-Pretty well-designed overall and a good bar for where other characters should be. Keep him the same, maybe improve his other 2 assists just so there might be some reason not to pick Tatsu every time when picking him.
Amaterasu:
-Put a time limit on holding Solar Flare (counter); 90 frames is plenty for a maximum.
-Decrease XF speed bonus to 20/35/50%
-Increase damage of beads attacks (s.:h:, cr.:h:, :f::h:, j.:h:)
Arthur:
-Remove hard-knockdown state when King’s Armor (Gold) expires. Replace with invulnerable soft-knockdown (as if TAC-countered).
-Add a dash when wearing no armor (stole this idea from someone else in here).
-Increase walk speed wearing no armor, slightly increase walk speed wearing standard armor.
C.Viper
-Very difficult character to fix without screwing up completely. My best idea is to move the first invincible frame on EX Seismo to frame 2, but I’d rather let people with move Viper experience chime in.
Captain America
-No changes
Chris
-Improve hitbox and frame advantage of s.:s:
-Decrease startup of Machine Gun
-Increase duration of Land Mine
Chun-Li
-Make cr.:l: hit low. I think she’d actually be pretty good with this alone.
Dante:
-Allow opponent to tech-roll out of Grapple
-Reduce invincibility on Vortex
Deadpool:
-Increase Hard Knockdown untechable time after 4th-wall crisis to allow for a followup combo with tight timing (similar to Devil Must Die).
Dormammu:
-Slightly decrease hitstun on j.:s: and cr.
-Slightly increase startup on Chaotic Flame
Dr. Doom:
-Decrease frame advantage of s.:s: to -4 on block.
-Decrease number of missiles fired by Hidden Missiles assist to 5 (but do not reduce vulnerable duration of assist call)
Dr. Strange:
-Make cr.:l: hit low
-Increase vertical hitbox size of :l:-Mystic Sword so it hits all crouching characters
-Slightly decrease startup of :l:-Grace of Hoggoth
-Increase frame advantage of s.:s: to -9 on block
-Decrease startup of flight
-Reduce recovery of successful Illusion to 1f.
-Allow Flames of the Faltine to pass through the opponent (possibly hitting more than once depending on Grace positions)
Felicia:
-No changes
Firebrand:
-Increase charge time of fully charged Demon Missile by 10-15 frames.
-Slightly reduce hitbox size of Bon Voyage
-Increase damage of Dark Fire; make last hit of Dark Fire cause Soft Knockdown.
Frank West:
-No changes
Ghost Rider:
-I don’t know what this character needs, I just know that he sucks right now.
Haggar:
-Add brief projectile invincibility to all versions of Violent Ax
-Second last hit of Rapid Fire Fist is untechable spinning (soft) knockdown.
Hawkeye:
-No changes
Hsien-Ko
[S]-Remove from the game, no point trying anymore.[/S]
-Significantly increase movement speed (walk, dash, air-dash)
-Senpu Bu can be canceled at any time.
-Increase travel distance of all versions of Henkyo Ki
Hulk:
-Better ground dash / wavedash
Iron Fist:
-Make Rising Fang Air-OK
Iron Man:
-Slightly increase hitstun on j.:d::h: and j.:u::h:
-Allow ground dash to be canceled earlier
-Last hit of Proton Cannon causes Soft Knockdown
-Slightly increase height of Iron Avenger hitbox
-Increase health to 1,000,000
[S]-Make him Invincible[/S]
[S]-Change all of his win quotes to “It’s spelled R-E-P-U-L-S-O-R”[/S]
Jill:
-I don’t have enough experience to say for sure but I think she is pretty well-balanced where she is.
Magneto:
-Remove ability to cancel blockstun with Gravitation/Repulsion/Attraction - it’s only a matter of time before this gets really broken.
-Slightly decrease recovery of Forcefield
-Increase startup of assist EM Disruptor, or change it to EM Disruptor.
M.O.D.O.K.:
-No changes
Morrigan:
-Cannot build meter during Astral Vision
-Reduce life to 900k
Nemesis:
-Improve his level 3. Seriously, do anything to improve it.
Nova:
-No changes
Phoenix:
-No changes
Phoenix Wright:
-I think he should get his invincible assists in Turnabout mode back actually but other than that I have no idea what this character needs.
Rocket Raccoon:
-Slightly increase hitstun on j.:s:
Ryu:
-Make Baku Hadoken OTG. It would require an assist to capitalize off of but I’m sure some creative players could make use of it.
Sentinel:
-Increase health to 1,100,000
-Make all and :h: normals cause chip damage
She-Hulk:
-Add Projectile Nullifying property to Lights Out!
-She needs more but I don’t know what else
Shuma-Gorath:
-Increase health to 1M
-Change Mystic Smash motion to :dp:
-Change Mystic Ray motion to :qcf: (this keeps both of these specials consistent with their respective hypers as well)
Spencer:
-Add damage scaling to Vertical Grapple.
Spider-Man:
-He seems ok as it is; maybe improve the hitstun on his normals for easier hit-confirms
-Replace his theme music with anything else
Storm:
-No changes, she’s perfect as-is. Maybe reduce startup on Typhoon and improve her assists somewhat.
Strider:
-No changes; the assist system change I listed earlier should bring him in line a little bit.
Super-Skrull:
-No changes
Taskmaster:
-No changes
Thor:
-New move: Hammer Throw (charge 
then :f:+:atk:). Different :atk: buttons determine startup and travel distance. The throw arcs slightly upwards and comes all the way to the ground at the end (giving him a projectile he can hit crouching characters with).
-Greatly reduce the startup of flight
OR
-Greatly increase the startup of flight, but greatly increase the movement speed and dash speed while in flight (not quite to Mad Beast levels, but close)
Trish:
-Slightly reduce duration of Peekaboo.
Tron Bonne:
-She’s a horrible character right now but I don’t know enough about her to know what could be improved given her current design. Buff something.
Vergil
-Increase startup of s.:l: to 6f
-Increase startup of cr.:l: to 7f
-Slightly decrease hitstun on s.:l: and cr.:l:
-Slightly (5-10%) increase travel speed (thereby reducing duration) of Round Trip
-Remove OTG property from level 3. I’m okay with it doing 600k and crumpling, it just makes no sense that it can OTG.
[S]-Rename Dimension Slash to Dubstep Slash - wubwubwubwubwub[/S]
Viewtiful Joe:
-See System Changes
Wesker:
-Reduce frame advantage on s.:s: to -4 on block.
Wolverine:
-No changes
X-23:
-:l:-Talon Attack always causes hard knockdown against airborne opponents
-Increase hitbox size of j.:s:
Zero:
-Reduce Special damage scaling minimum damage to 20%
-Increase time required to fully charge buster by 12 frames
-Reduce frame advantage of j.:d::h: to bring it in line with j.:h:
-Increase startup of j.:h: and j.:d::h: by 2f
-Only 1 Raikousen (lightning) allowed per jump (just like Hienkyaku)
[S]-Zero’s call-out when entering the battle after the defeat of a female team-member should be “WHATAMIFIGHTINGFOOOOOOOAGH”[/S]
then :f:+:atk:). Different :atk: buttons determine startup and travel distance. The throw arcs slightly upwards and comes all the way to the ground at the end (giving him a projectile he can hit crouching characters with).