Ok basically when you shoot a regular fireball people will parry it but i have discovered a way to makle the fireball really hard to parry and that is Kara-fireball. For instance jab fireball kara’ed will be good cuz if your in their face their will eat it before they jump. Also another reason is because the spacing on the screen gets affected so it causes them to time it again on reaction. Beleive me it works i used this on Issei numerous times on his ken and chun. Or you can kara strong fireball which is also useful. Characters you should really kara fireball:
CHun with no meter.