EX Rainbow isn’t really good for cross-ups against anyone decent. I mean, you can still use it to try to confuse them by wiggling one direction then going the other way over their head at the last second, but that’s not going to work very often against a seasoned player. The reward isn’t worth the potential damage you’re going to take most of the time when they block or focus it. EX rainbow is good in certain situations, to get out of a tight spot. It’s also good to finish someone off in a close match with its chip damage, it does very little chip damage but sometimes that’s all you need when they have basically no life left. His j.mk is the main entry for his cross-up game, plus his hop, it just depends on the character you’re going against. You don’t want to jump around too much against shotos, even on wake-up they can punish you by mashing out an uppercut. I still do it but it takes good timing. You almost have to wait to see what they’ll do on wakeup.
Try to remember that you never ever have to jump forward against a Ryu player, that’s 90% of their game, getting their opponent to jump forward for cheap damage. You never ever have to take fireball chip damage from them either. You can coward crouch, neutral jump from a distance, and be prepared to throw out a hp while you’re up there if they try to jump at you. You’ll stuff them pretty much every time if you time it right. Plus, you can slide under them for a free hit, but you have to be careful to only do that on quick reaction to a fireball from mid screen or less. Then, if you have EX meter of course you can roll right through them, try not to waste it at full screen unless you have really good reflexes and can toss it out the instant their fireball animation begins. The EX forward rolls also go through Ryu’s super and ultra fireballs. There’s a matchup thread in here somewhere. You should check that and come back with specific questions on a matchup you have problems with. Other than that, work on your combos and poking game. Most Blanka players I see rarely utilizes his hands and feet very often. Don’t fall in love with just using your balls. lol Learn every matchup, every single one, you never know who you’re going to face in a tournament. You may be a less skilled player than someone you’re going up against, but if you know the matchup better you might be able to beat them.