General

What does the tier list look like?

WW = World Warrior (Normal)

CE = Champion Edition (Champ/Dash)

HF = Hyper Fighting (Turbo)

S = New Challengers (Super)

ST = Super Turbo (SuperT/SuperX)

Banned:
ST-Akuma

SSS:
CE-Bison
CE-Guile
CE-Ryu
CE-Sagat

SS:
WW-Guile
HF-Guile
HF-Ryu
CE-Ken
HF-Ken
HF-Sagat
ST-Dhalsim
ST-Balrog
ST-Ryu

S:
WW-Dhalsim
HF-Blanka
ST-Chun-Li
S-Ryu
S-Ken
ST-Ken
ST-Honda
ST-Dee Jay
ST-Sagat

A:
HF-Honda
HF-Zangief
HF-Balrog
S-Balrog
S-Bison
S-Sagat
S-Chun-Li
S-Vega
S-Dee Jay

B:
ST-Blanka
HF-Dhalsim
HF-Vega
S-Honda
ST-Fei Long
ST-Guile

C:
WW-Chun-Li
CE-Chun-Li
WW-Blanka
CE-Blanka
CE-Balrog
WW-Honda
CE-Honda
HF-Bison
S-Fei Long
S-Hawk
ST-Zangief
S-Guile

D:
WW-Ryu
WW-Ken
WW-Zangief
CE-Zangief
S-Zangief
ST-Hawk
S-Blanka
S-Cammy
ST-Cammy

(Version Breakdown: Best-to-Worst ranging Left-to-Right):

Ryu: CE, HF, ST, S, WW

E. Honda: ST, HF, S, CE, WW

Blanka: HF, ST, WW, CE, S

Guile: CE, WW, HF, ST, S

Ken: CE, HF, ST, S, WW

Chun-Li: ST, HF, S, WW, CE

Zangief: HF, ST, CE, S, WW

Dhalsim: ST, WW, CE, S, HF

Balrog: ST, HF, S, CE

Vega: ST, CE, S, HF

Sagat: CE, HF, ST, S

M. Bison: CE, ST, S, HF

Dee Jay: ST, S

Cammy: ST, S

Fei-Long: ST, S

T. Hawk: S, ST

Miscellaneous

-WW characters cannot participate in mirror matches against themselves.
-Balrog (boxer), Vega (claw), Sagat and Bison (dictator) can only be chosen from CE and onward.
-Likewise, Cammy, Deejay, FeiLong and T.Hawk can only be chosen from Super and Super Turbo.
-After getting up from being knocked down, you are unthrowable for 13 frames.
-Not all characters get dizzied at the same rate. In order from easiest to dizzy to hardest to dizzy:

Sim, Claw
Guile, Cammy DeeJay
Boxer, Blanka, Chun, Honda, Fei, Ken, Dictator, Ryu, Sagat, Hawk, Zangief

-Blanka's stage is the widest, and Claw's stage is the shortest.
-Boxer's Strong throw has more range than his Fierce throw, even though they're the same throw.
-After being knocked down, different characters get up at different speeds.

--Some of this info is an excerpt from NKI's edit of the ST wiki.

What game versions are there?

Playstation 2

This version is a perfect port of the asian version of the game. It has the difficulty setting of the non-japanese ST boards (which have lower difficulty setting). There's the common knowledge that ST-Vega's(claw) off-the-wall (done D,K,U instead of D,U K) dive is miss-mapped on the inputs due to a porting error; however, in both the asian and japanese arcade boards the input recognition of that move is flawed as well.

CapKore PS2 (Japan only)

This version has the Vega (claw) off the wall dive input corrected and Super Sagat's low tiger shots have their original 37 frame recovery window instead of the 45 frame recovery they initially had in this version.

Xbox

This version is technically identical to the PS2 version, only difference is that it can be played online.