How to get sources(Luck Source, Power Source and so on).

First, make sure you have:

Morph Materia. If you don´t have it and don´t know where to get it, Google is your friend ^^

The Submarine(so you can travel under water).

Tip: Give Cloud Ultima Weapon(his strongest weapon) and make sure he have 9999 HP(works easiest with HP Plus Materia on MASTER). You could run into an enemy which can use Abnormal Breath, which makes one of your characters confused. So, give all your party members(if possible) Ribbon. But if you only have one, give it to the one which deals most damage(and that should be Cloud if he have Ultima Wepon and 9999 HP.)

How to do it: Enter the Submarine and get to the sunken Airplane( it isn´t so far away from Junon, so if you´ve travaled very very far you can be very sure it´s the wrong way). Then, when you walk/run, you will probably run into enemies. These enemies have much HP, and some of them could damage about 3000, but probably less. When you meet a monster, make sure the last thing you do is attacking them with Morph. Remember: Morph makes you damage much less than you usually do. If you do that on the monster which can use Blaster and have a tail, you will change it into a Power Source. If you do it on the monster which is green on the top and looks like a jellyfish, then you´ll get a Luck Source. There´s more monsters, but you could find out the rest.

So, you´ll need Morph Materia and the Subarine.

And, if you want to make it easy for you: Give Cloud Ultima Weapon, Morph, and HP Plus so he has 9999 HP and give all your party memebers Ribbon.

To make it even easier, give all Power Sources to Cloud(if he is the one having Morph).

Ask if there is a special source you´d want to have, I might remember which monster has it ^^