I usually attack people in splinter cell style, attacking behind or being on top of them and try attacking them with my energy sword.
And I usually use sniper rifles from high places to attack others in low ground.
And I always Lock-on vehicles with my rocket launcher all the time.
Does this have to be on X-box live or can it be on mutiplayer or both?
Sometimes I like to act stupid and just charge and end up dieing... Sniping and fun to because they just get shot out of no where. Oh an another dumb things that I do is have a friend with a rocket launcher and just jump on the banshee while another guy drives it. He can lock down other people but you cannot do any tricks on it or you will make the guy fall off or do sharp accelerations/turns.
If I can attack from behind (obviously) I will melee them on the back.
Any, it because I sometimes do that to computer players too

Offensive: Throw grenades and charge.
Defensive: Throw grenades and back off.
Of course there's a little bit of melee, dual-weilding, and general ownage in there somewhere.
I havnt played it in at least 3 months but my style is almost exact for every game.
-While some idiot is sniping (trying to) me out, blow them away with the shotgun from behind.
-Move and shoot, preferably, if your a TS vet, move extremely rapidly in rotating circles while keeping the shots on your foe.
-Rocket launcher is supposed to be used in every situation, if your up close and somehow didnt switch to a blade, SMACK! Or... I somehow get away with firing it up close.
-I have a unique style, you gotta play with me, too hard to explain.
GENERALLY FOR ALL SHOOTING GAMES------
Hmm, i cant say how good i am, cause ive only played my family. And i dont want to brag at all, but generally, i own them all. I dont care, get my cousins and brother vs me. Ill beat them. But that could be them, i could be bad, i need to try online play.
Yeah, online is much harder, mostly. Because you never face like "the best of the best" so to say when you are not online. So you just keep getting better and better as you face harder people.
I love driving, and sniping, mostly. I go for an HS all the time, unless I might die. It's not that hard for me to get them too, just about all my snipes are to the dome.
What I don't like about halo 2 in xbox live, you get to challenge higher ranks who are better than you.

I hate playing against people lower leveled than me. It pressures you to win and most of the time, i succumb and lose

Offensive: Dual wield with SMG and Plasma Pistol or... SHOTGUN!!! Most of my friends hate meeting me on small maps with a shotgun

Defensive: Whatever I have...
O.o I have another attack style, Any Dualable Gun and Plasma Pistol. I hold the plasma pistol, wait for the enemy and fire. then use my other gun to finish him/her off.
I like defence, Expecially in XBL, On Halo 2... I don't know why though, I just like to defend out flag and all those kinds of things.
O.o I have another attack style, remember they can't see you in the radar if you're holding the left thumbstick? I tryed that, it's like splinter cell style. Except no darkness.
ADDITION:
Except that it's in FPS style, not TPS like splinter cell.
Lol, Evrey one crouches when they get shot and no one is near them.
There like "WTF WHO SHOT ME, MAYBE IF I CROUSH THEY WILL LOSE ME"... Next you.. Tink..Tink... GRENADE...
If you crouch, they can't see you in the radar.

My Defence hmm I never play Defence. I am always attacking. I like getting close and making the BR that people love to whore now useless. Close Range and Vechile combat is my game and I never have Defence I am always attacking the enemy and If I am low on shield I run then try to flank my enemy or catch them off guard or blantenly charage them like a mad man.
I could bring a video of me doing Splinter Cell style in halo 2 on xbox live... My camera has a bad quallity on recording the T.V. and nothing else.
Offense: Kill them before they kill me
Defense: Kill them before they kill me
But more than half the time, i fail

Offensive: Suicidal Attack with Anything I have
Defensive: Somewhat tactical, ( Hide + Dual Needlers )
Needlers kill them no matter what if you aim right, and shoot about 5 seconds backing up and they are all with needles... 0.5 seconds past ( BOOM! )
Sometimes you need a grenade to kill them, unless you suck at aiming with a grenade.
Throw down a dual weapon, throw a grenade, then pickup the dual weapon again.
Shouldn't your defensive tactic be the exact same as your offensive one? Because both serve one purpose: To kill your enemy.
Whenever you attack someone, you must be offensive
Whenever you are being attacked by someone, you must counterattack, therefore must use offence.
Somebody could use defense with a (B) attack and attack with a [R] button.