As always, his Hadouken (fireball) and Shouryuken (dragon punch) are good attacks, and now the Hadouken can be done in midair. Channeling the power of Akuma by pressing F,D,B,SP, or Ken with F,D,B,MP (you have to at least be at combo level one) is a very good idea. You can change back to regular Ryu with F,D,B,WP, which also burns a level of power. Ryu's best Hyper Combo is the Shinkou Hadouken (D,F,MP+SP), which is a jacked up version of his regular fireball. Akuma's fireball super is D,B,MP+SP, and both his and Ken's best super is D,F,MP+SP, the Shouryu Reppa.
Speed is your best asset with Chun Li. Use the lightning kick liberally, and don't be afraid to jump in, hit your foe with a combo, and jump back out. Her best Hyper in the Senrestu Kyaku (D,F,MK+SK), an advancing, psycho lightning kick. Use the Kikou Shou (D,F,MP+SP) if your opponent attacks relentlessly.
This guy is the king of cheese, and great for beginners. Use the shoulder cannon often (usually it'll blast right through others' projectiles) and stay away from your opponent. Use the Proton Cannon (D,F,MP+SP) if you have time; otherwise, use the weaker but quicker War Destroyer (D,F,MK+SK).
Wolverine is another good one for beginners with his long-range, quick regular attacks. Use the berserker barrage or its Hyper counterpart (D,F,MP+SP), the Berserker Barrage X, if your opponent puts him or herself into a stall. Finish combos with the Fatal Claw (F,D,F,MK+SK).
He's slower than most other characters, but he packs a mean punch with his staff. Use the kinetic card often, both on the ground and in the air. The Royal Flush (D,F,MP+SP) is the best Hyper; you can use the Cajun Explosion (D,B,MK+SK) against a charging opponent.
Captain Commando is a very good long-range fighter. Keep opponents away with the Captain fire and Captain corridor. The Captain Laser super (D,F,MP+SP) is quick but ineffective against someone on the ground; The Captain Storm is great if it connects, but can easily be blocked.
Slow but strong, Zangief is good for experienced players. Throw people as much as you can, and do NOT change into Metal Zangief unless you're really good with the big Z--he can't block! His best Hyper is the Final Atomic Buster (360 degrees,MP+SP).
Strider's speed, combined with his power in combos, make him a formidable foe. Don't use specials unless you feel the need; use the Hypers as often as you can. Both the Ouroboros (D,F,MP+SP) and the Legion (D,F,MK+SK) are good attacks.
Also a slower character who packs a mean punch, Cap also has a long reach to work in his favor. The charging star and the stars&stripes are good attacks, and the shield slash (use MP for a straight and true flight) works well long-range. Use the Final Justice (D,F,MP+SP) against the computer and anyone who doesn't know what a block is, otherwise use the Hyper Charging Star (D,F,MK+SK).
Hulk doesn't have any quick attacks, so rely on your strength and reach to score hits. The gamma charge and gamma wave specials are good attacks. As far as Hypers go, use the Gamma Crush (D,B,MP+SP) if your opponent is overhead, and the Gamma Wave (D,F,MP+SP) if they're staying on the ground.
Nicknamed "Spastic Boy" for his psychotic appearance and demeanor, Jin also packs power (and a gigantic robot) behind his attacks. Use the Jin tornado often, and a good normal attack is the squatting SK. The best super by far is the Blodia Vulcan (D,B,MP+SP), which covers the whole screen. To counter aei\rial attacks, use the Great Cyclone (D,F,MK+SK)
A quick character, Morrigan can also do a ton of damage if used correctly. Use her fireball to keep enemies at bay, and use her drill (D+SK in air) if you get above someone. Use the powerful but slow Darkness Illusion (D,F,MK+SK) against the computer, and the faster Soul Eraser (D,F,MP+SP) against humans.
Use the Venom fang liberally, and use the Venom bite as your long-range attack. Keep foes at medium distance so that you can utilize his medium-range speed and power. As far as supers go, the Venom Web (D,F,MP+SP) takes out a ton but can easily be blocked, and the Death Bite (D,F,MK+SK) can be used quite effectively against a hard-charging opponent.
Spidey is best utilized like Strider--use specials sparingly, and rely on normal kicks, punches, and combos. Unfortunately, his Hypers are easily blocked, but if they connect, they'll cause beaucoup damage. The Crawler Assault (D,F,MK+SK) is his best, but the Maximum Spider (D,F,MP+SP) and Ultimate Web Throw (D,B,MP+SP) will cover the screen and achieve similar results.
Megaman's strength lies in his regular cannon. Pressing the strong punch button will send a fireball across the screen; this is a very good move to use frequently. If you have time, hold the button and charge it up to create a more powerful blast. The best super is the Hyper Megaman (D,F,MP+SP).
On the character select screen, you can also select your "Special" character. The machine runs through the roster like a roulette machine, so it's difficult to actually "select" the character you want. However, there are two characters you can get that aren't on the roster, and if you do these you'll get them every time.
For the Sentinel, hold start, SP, MP, and MK right after you select your second character (or once the "stage" screen appears showing your next opponent, if your characters are already selected) and until the Sentinel flashes as your helper.
To get Shadow, hold start, WP, SP, and MK.
In addition, you can get some of the regular special characters with button sequences. To get Juggernaut every time, hold start+WP+MK. For Psylocke, hold start and MK only.
One of the sercet characters, as mentioned before, is Roll. To get her, move the cursor to Zangief and move in the following manner: 2 left, 2 down, 2 right, 2 down, 2 left, 1 up, 1 right, 2 up, 2 right. After this sequence you'll be on a Roll!
To get Shadow Lady, place the cursor over Morrigan and move in the following manner: 1 up, 2 right, 4 down, 2 left, 4 up, 2 right, 2 left, 2 down, 2 right, 2 down, 2 left, 2 up, 2 right, 2 up, 2 left, 5 down. Shadow Lady will appear below Gambit.
Sometimes, during the first portion of the battle, Onslaught will call another character (without much energy, thankfully) to fight you. This cowardly display will cause you extra hassle, but just defeat whomever he throws at you as you normally would. If you wait long enough, they will go away, but it's advised to finish them off as quickly as you can, and by suffering the least amount of damage.
Part two of Onslaught is much easier, if you play it right. The first thing you should do is jump up and lightning kick Onslaught's head (it seems to be his most vulnerable spot, although his other parts can take damage too, if they sneak into the foreground), continuing until he KO's her. When your next character comes in, just punch his head until he's gone. Remember to super jump over him when he says "Behold my mighty hand" and sweeps it across the surface, and to also super jump over the Hypergrab. Block the energy beams he shoots (if you don't, you're in SERIOUS hurt) and jump kick the flying robots which rain down the fire on you. Also, beware his regular punch attack, but also be aware it won't hurt you as much and will leave more of him vulnerable to attack.
If you don't use Chun Li against the first Onslaught, you can use Jin, Wolverine, Hulk, Venom, Captian Cheap *ahem* Commando, War Machine or Megaman fairly effectively. Block his attacks (except for the Hypergrab) and return fire when he stalls, with the following specials (respective to the previous owners): Jin tornado, berserker barrage, gamma charge, Venom fang, Captain kick, shoulder cannon and Mega buster (charge it while you're blocking). Beam supers work pretty well against him too, but wait until he does the Hypergrab and your beam will pass right through it.