A F0xy Grampa
This is easy to understand. If you know what you're talking about then this is between me and you and nobody else.
Flashes gimmicks.
Every single mid hit he has is duckable. Literally. Even b22 can be ducked with certain hit boxes.
Strings to be back dashable?
B22, back dashable (+3 on block???)
D1D2 (nuetral, back dashable)
F213 (back dashable) +10 on block.
Punishing those back dashes..
B22 you can jump in for a punish, unblockable. but, is this really practical? think about this. What if they don't jump in. JI2 is -4 for flash and can be interrupted. In the elite game and studying flash, flashes jump ins are worthless. and if done on a wrong read it can cost a full combo punish.
D1D2, well, if blocked low its nuetral. it puts flash at a higher risk, lightning charge is too unsafe and everything he has is back dashable.
F213, back dashable. If going for lightning charge, it is blocked, -21, or you go COMEPLETELY through their body due to invincibility frames. F213 is also duckable during 2. also, F21 is -26 on block, and the next move on start up is 20. Meaning, you can full combo interrupt this, which you can.
Getting in
Dash blocking is easy, but the fact flash has to take 8-10% chip damage before getting in is outrageous. using projectile phase is almost... impossible. you can't react to do it, you have to know its coming.
Flash has a chip damage disadvantage. all of his specials are unusable on block. and still do shit chips.
Most characters get good chips off of projectiles, well flash has none.
to make up for that you can give flash low chip damage on normal moves, and give him correct jails.
1-3% chip on is strings is very fair.
Making his lightning charge safe, fair because he has to chase you like a dog, and he can't get any super big combo damage off of it like killer frost with her slide. plus, it is interruptable on reaction so even still flash players must think twice before using it.
Appropriate buffs?
Give him a good inside jailing game by increasing frame advantage, or less pushback.
Make some of his moves safe.
give him a little bit of chip on normals because of his lack of special move use.
Make lightning charge safe.
Give him a nice anti air.
Projectile phase to be used on reaction.
with these buffs, give flash damage nerfs.
Nerfs:
Nerf all of his 50%'s down to 36-42%.
Even with this idea of the flash, you know that there are still flaws and punishable ways. RMS stance is unsafe. that is a perfect example. you can do this. I know you can.
right now what flash is he has to kill himself to get in, and then he is at an disadvantage, even on rushdown.