For Yoshi OoS, you actually don't need to use the action state hack at all, simply rewrite the shield functions' interrupt exceptions in main.dol to include jumping. The game takes care of the rest. The issue with Yoshi OoS is that Yoshi suffers only half the shieldstun everyone else suffers. Combine that with jump out of shield and you get nasty results. Great for Yoshi though!
Regarding Ness having a "Shine:" Ness in 3.1 will be a treat for Ness fans. No shine, but honestly, he has everything he needs to get the edge on opponents. Do remember the silly things you can do with Ness in Melee 1.0. Having a semi-real recovery is one of them.