To get around Ruby weapon's sandwhirl spell, you must go into battles with 2 characters dead. To do this the fastest way, use HP<->MP on the characters you want to kill and then enter a random battle and kill them.
Here is a good method to beating Sepheroth in the final battle: First of all, make sure your characters have either Ribbons or Tetra Elementals equipped in battle.
- Cast DeBarrier
- Cast "Big Guard" enemy skill
- Cast Regen
- Cast Knights of Round
- Cast Bahamut Zero (linked with quadra magic)
- Mime it
- skip 2 characters and mime it again.
Use any other powerful attacks you have. Use your Limit breaks as much as possible. If any character dies, use phoenix to revive them.
Easy ways to level up on Disc 1
Most people don't like to spend hours running around fighting low-exp monsters early in the game JUST so they can be strong enough to stand a chance against powerful bosses such as Lost Number. A quick yet risky way to gain MANY levels with patience, time, and about 30 Gil is to journey back to Junon. The ideal party for this task would be any characters with long range weapons- Barret or Yuffie (Figuring that you're doing this to be able to fight Lost Number), and Cloud with the Long Range Materia equipped. Make sure all characters are in the back row, have protection against poison, and one with restore materia, because these monsters can do 400+ damage to you. When you arrive back at Junon, keep running right until you come to a grey area shaped like a T, with soldiers drilling at the far left. Beside the red soldier, on the back wall, is a small box which you should go to and examine. Press the X button, and the screen should flash red, accompanied by a siren. Run! around until you get into an encounter, in which you'll either face strange reddish-pink monsters or a giant robot. The pink monsters give you 700 EXP EACH while the robot monsters give you 900 EXP each. Keep your HP high, and run back to rest at the inn for a mere 30 Gil once your MP are depeleted, and you'll be able to face Lost Number in no time.
Quick AP on Disc 1
Once you acquire the Tiny Bronco, equip your characters with Double growth weapons (Cloud's Force Stealer/Rune Blade, Barret's W-Machine Gun/Drill Arm, Aerith's Wiser/Wizard Staff, Cait's White/Black M-Phone, Red's Magic Comb/Plus Barrette, Tifa's Morot Drive/Power Soul/Platinum Fist, Vincent's Peacemaker, and Yuffie's Wind Slash/Twin Viper. Also, if you missed/sold these weapons, or need more double-growth slots, Platinum Bangles can be used. Place the materia which you want to receive boosted AP onto the double-growth weapon/armor, and head past the Temple of the Ancients. On the far Right of the map is the town of Mideel, which isn't able to be visited as of yet. Find a shore and exit the Tiny Bronco, then run along the coastline until you run into a large blue worm. It has 9000 HP, but what this monster has to offer will make it well worth the effort. Upon its defeat, you receive 200 AP! And since you have materia in double-growth equipment, each will receive 400 ! AP with each worm you kill! The 1300 EXP and 5000 Gil are a treat as well, making this area a great place to gain Gil and level up your materia. If you bought HP or MP Plus materia, this is also a nice place early in the game to increase it by one level.
Unlimited Tetra Elementals And Ribbons
To get unlimited tetra elementals and ribbons, you must morph Cactuar into a tetra elemental and a Tonberry into a ribbon.
How to beat Guard Scorpion
This is a really easy fight. Have Cloud cast Bolt and have Barret attack. Make sure you use your Limit Breaks when you have them. When the Guard Scorpion has his tail up, it's healing time. You don't want to attack him when his tail is up because he will counter attack and take a lot of HP's away. When his tail goes down again, just cast Bolt and attack. After the fight, you will get the Assault Gun.
How to beat Air Buster
Have Cloud and Tifa Cast Bolt and have Barret attack. Make sure someone knows Cure because Air Buster will take a lot of HP's away from your party. Heal often, and make sure you use your Limit Breaks. Follow this and you are on the road to victory.