Might as well kick it off here with this nugget for Vega:
Option selecting meaty cr.LK with Ultra 1 has the following effects:
Against Back Dash
Full Ultra 1
Against KKK Single Back-flip
2nd hit of ultra lands and goes straight into animation for 435 damage, plus the damage from the knockdown.
Against PPP Double Back-flip
4th hit of ultra lands and goes straight into animation for 435 damage, plus the damage from the knockdown.
The cr.LK stuffs everything but Ultra 2. Everything. Really.
Essentially, using this means Vega can only block, or wake up Ultra 2, which is pretty nifty IMO.
And of course, if you do stuff something or they don’t block appropriately you’ve done cr.LK, st.LP and can combo regardless, provided that you’re ready for it.
[NOTE] - Do not use near the corner. Only use mid screen where you’ll land the ultra before you touch the wall. If you do touch the wall before you land the ultra, you go through his back-flips and Vega will end up behind you with time to punish and you’ll likely end up in his vortex.
Other than that, if the timing is right it’s really good for back dash/back-flip happy Vegas.