Ryu/Ken Matchup

Hadouken
-Can Ex.Sky High Claw thru fireballs for a hit if done early in fireball
-Can Ultra thru it with more relaxed timing that Sky High Claw, but moer difficult input.
-Can 3K backflip at range

Shoryuken
-Can Lk.Scarlet Terror - Ex.Scarlet Terror after block
-Can DF.Hk - Ex.Izuna after block
-Can bait waking SRK for Ultra
-Can 3K Backflip SRK on reaction

Tatsu
-Can Cr.Mp to keep them at a range
-Can Lk.Scarlet Terror - Ex.Scarlet Terror(Don't use for light tatsu or ex.tatsu)
-Can Ultra full tatsus from halfscreen & back

Crossups
-Many crossup attempts can be stuffed with either standing or crouch lp
-Do NOT attempt to Scarlet Terror crossups, you'll lose out on an early hit, or whiff completely

General Strategy:

Ryu & Ken are similiar enough that you can fight them both almost exactly the same. All Vega's love to have some breathing room, so keeping atleast halfscreen is a good plan in most instances, keeping in your poking range, and forcing your opponent to come to you. Avoid being cornered, it's Vega's greatest weakness, if you can, make good use of his wall jumps to try and keep the fight center stage. Baiting SRKs is a win strategy for Vega here, any whiffed or blocked SRK can give you up to maybe 30% of your opponents health bar. Do not attempt many Izunas without leading in with a combo, Ryu/Ken have many tools to deal with these.

Ryu:
Alot of Ryus will try to fireball you at long ranges, use these moments to build up you ultra gauge, absorbing & jumping when need be. If they attempt fireballs while you have your back to a wall, you can wall jump - J.Hk - Cr.Mp - Ex.Izuna for easy damage.