Street Fighter Alpha 3/Modes and ISMs

(Note: Much of the info provided here is taken from Kao Megura's SFA3 FAQ.)

Comparisons at a glance
* Does not include Super Combo damage.

X-ISM

 * + Longer Guard Power Gauge length (so it's harder to get Guard Crushed).
 * + All attacks, excluding Super Combos, do more damage.
 * - No air block.
 * - No ground recovery roll.
 * - No Alpha Counters.
 * - No Taunting (except for Dan).
 * - X-ISM characters have only one predetermined Super Combo.
 * - They take slightly more damage from attacks (blocked or not).

A-ISM

 * + Air blocking.
 * + Both ground and air recoveries
 * + Alpha Counters (these cost 1 level of SC power and 1 notch of your Guard Power Gauge).
 * + Taunting (once per round only, excluding Dan).
 * + SC gauge charges up faster than X-ISM's SC gauge.
 * + Access to all Super Combos (excluding Dhalsim).
 * - Damage per hit is average (less than in X-ISM).
 * - Guard Power Gauge size depends on character (certain characters are easy to Guard Crush).

V-ISM

 * + Air blocking.
 * + Both ground and air recoveries.
 * + Alpha Counters (these cost 50% of a full OC gauge and drain 1 notch from your Guard Power Gauge).
 * + Taunting (once per round only, excluding Dan).
 * + Determine which range of attacks you'll use (far or close), by leaving the controller neutral or holding it back when you press Punch or Kick (Does not apply to all characters).
 * + OC gauge also charges very quickly.
 * + Use Original Combos instead of Super Combos.
 * - Damage per hit is lower than in any other mode.
 * - It costs half an OC gauge to use an Alpha Counter.

Classic Mode

 * The damage rating is the same as in X-ISM (x1.2), and the gameplay is also the same (i.e. Chun-Li is in her SF2 outfit and has moves like the Sou Hakkei, etc.)
 * In addition to all of X-ISM's restrictions, you lose the ability to air recover, reduce block damage, or reduce damage taken.
 * Furthermore, you have no Super Combo gauge and no Guard Power Gauge.

Mazi (Serious) Mode

 * The damage your attacks inflict is considerably increased, regardless of the ISM used.
 * You take double damage from any attack.
 * Your opponent only needs to win one round to defeat you.

Saikyou ("Strongest") Mode
(Note: Saikyou is a reference to Dan's dojo and the interpretation of "Strongest" is meant to be sarcastic.)
 * The damage your attacks inflict is slightly lessened regardless of the ISM used.
 * Your Guard Power Gauge is drastically shortened.
 * You cannot cancel a ground attack into a special move.
 * You can get dizzied easier (your resistance is halved).