how do you beat him w/o gameshark and with out get'n those cool items you get from the pocket station mini-game?

i've never beaten it (Duh, u know that Roneo--we're related), but there is a really helpful (or so i've heard) article in the official stratedgy guide. check it out.

I've beaten him once (I tried like 9-10 times). Make ur best junctions and make sure u have some strong resistance to status changes, draw Ultima from him (which is probably stronger tehn urs and never runs out) make sure u have some full lives and aura's cuz u'll need them, make sure everyone who's fighting has his/her strongest weapon/limit break. Keep attacking him with strong magic or guardian forces use Carbunkle to cast reflect on u and cerberus for triple magic do do some more damage, after a while he'll die and u'll get a walkthrough on how u defeated him, it really isn't nesecary to defeat him for the game since it adds nothing but it is really the biggest challenge there is.

Junction Ultima to your strength make sure it reaches 255 for all the characters, make sure you also have 9999hp and that your vitality rate is maxed up (255 preferbaly, but close by is good as well)
Have death junction to your status defense as well
What I did is letting Squall and Zell cast Aura on themself, 3rd party member does Holy War, (can refine from Gilgamesh card) and then let Squall and Zell attack with their limits and 3rd Party member cast meltdown. When Holy war wheres of do the same again, if your party gets some big damage, use a mega elixer (also to be refined from a card) and let another person do holy war.
It worked from me ^_^

<font color=red face="comic sans ms">Unlike the other enemies in the game, Omega Weapon actually has an order to his attacks:

~ Lv5 Death
~ Meteor
~ Medigo Flame
~ Gravija
~ Terra Break
~ Ultima
~ Light Pillar
Then back to Meteor.
(I think I got that order right, I'm just doing that from memory... :uh?: )

So make sure you have Death junctioned to status defence if your levels are a multiple of 5. ;) You will need to have 9999HP, because Medigo Flame causes 9998HP damage to all of your characters. Terra Break is your main problem though. You will either need to use Rinoa's limit break Invincible Moon, the items Hero/Holy War, or the Defend command so that you don't take any damage from this, or it will probably do enough to wipe your party out 2-3 times. Light Pillar is 9999HP damage to one character and impossible to defend against (I'm sure you'll know this if you already fought Ultima Weapon. ;))

Use Meltdown as early as possible, then give Auras to Squall and Zell. Use their limit breaks a lot. If you're not very good with Zell's Duel, practice. Use the moves Punch Rush --> Heel Drop --> Mach Kick over and over because they always chain onto each other, and they are easy enough to do. They might not be the most damaging moves, but you can do them very quickly, so you will do a lot of damage with them. Alternatively, you can just use Punch Rush --> Booya over and over, that works too. :)

Squall, use Renzokuken, and hope for Lion Heart. ;) Although once you're good enough at Duel, you can effectively do more damage with the Duel than a Lion Heart.

Or, if you still find it too hard, here's the easiest way: Give Selphie Aura early on. Search through her limit breaks until you get 'The End'. Use it. Instant death to Omega. :D You might think it's cheating but it's nto as the game allows it, but it's not really a good way of saying you beat Omega if you use it, is it? :p ;)

I used Teknos technique with the Holy Wars. Meltdown, aura, limit breaks are really all you need to win this battle. Oh yeah Lionhart would really help too.

Now some people I have talked to say they run out of Holy Wars and end up dieing. I know the trick that will get you as many Holy Wars as you want. First, card mod Gilgamesh and get 10 Holy Wars. Then go to the Ragnarok, assuming this is Disc 4, and go to one of the Card Players from Balamb Garden. Eventually one of them should have the Gilgamesh card again. So just win it again and card mod. This can be done with any high level card and can be done as many times as you want. Just be patient because sometimes it may take some time to find a specific card.

The simplest method was (for me anyways) to refine Gilgamesh into 10 Holy wars and the laguna card into 100 heros (which you then have the option wheather or not to refine those 100 heros into 10 holy war-trials) you will also need loads of auras. Start the battle with 100 deaths junctioned to your status defense, because otherwise level 5 death will completely take out your entire party if your on level 100 (which you most likely will be) The first move you should use is aura use it on Squall and Irvine or Zell, then after two of your characters are aura uped so to speak have another character use a holy war, and keep using limits until the holy war wears of then repeat this process (healing where it's needed) and the battle should take around twenty minutes.