Well I took a look at some of Vega’s frame data.
This Vega (and probably most others that know their character) are most likely to crouch tech with cr.mp. Vega’s cr.lp, cr.lk, and cr.mp all have a startup of 4 frames, so there’s no reason not to. Vega’s crouch tech is 0 on block because of his cr.lk, but this combined with cr.mp, becomes -4, which should technically be punishable with shorts into scissors. However, the push back from this most likely puts you out of range for a cr. short (haven’t tested this yet though). His cr.mp can hit when you are literally standing 1/2 screen. Bison’s st.mk can sort of counter this (but has a 6 frame startup compared to Vega’s 4), and the trade is pretty reasonable.
Vega’s cosmic heel (startup 14, -3 on block).
Most Vega’s will follow up a blocked cosmic heel with a throw attempt, but they really shouldn’t be able to land the throw, since all throws take 3 frames and Bison has a 3 frame crouching short.
Vega’s overhead aka “Piece of Mercury” (startup 20, -4 on block).
This unique attack is 0 on hit, so Vega shouldn’t be able to follow up with anything else.
Flying Barcelona Attack
If Vega decides to followup his Flying Barcelona Attack (wall dive) with an Izuna drop attempt, jump the other way with HK or do a late teleport. If Vega doesn’t do the followup, and uses it as an escape mechanism, Bison can teleport towards (think it’s the dp motion + KKK version) to meet up and punish (as displayed by Neurosis during Canada Cup).
If Bison decides to use EX psycho crusher as an escape tool (as I did too many times to escape the corner), Vega can punish this with EX FBA fairly easily.
Scarlet Terror (HK/EX versions startup 4, -15 on block)
If Vega plans to anti-air you, these will be his go to options. The major downside to this special is that it requires Vega to have down-back charge, so corpse hopping or a straight cross up will negate Vega’s wakeup game. I think it also has pretty average priority and tends to trade a lot.
Backflip (PPP = recovery 65, KKK = recovery 42)
There isn’t any frame data for startup, so I guess there must be some frames of invincibility. Don’t think it’s a get-of-jail free card. I’m not sure how punishable this is. You might be able to option-select slide (like for backdash), but I haven’t tested this.
Sky High Claw (startup 15???, -20 on block, EX startup 10??, -18 on block)
Not used much. Pretty punishable on block, but sometimes they may land further away than usual. Just be aware that if Vega heads for the wall behind you, that you block the other way.
Rolling Crystal Flash (-2 on block)
Can be stuffed on startup, but is perfectly safe on block.
Recently, I just found out that st.lk was +3 on block and startups in 4, which makes it pretty damn good for tick throws and frame traps.
But this time I don’t know… I forget it? shame on me hahahaha.