Cloud? In Final Fantasy Tactics? Yes! He's not that great of a character, but he is there. And there are some really neat characters you'll get on the way. First of all, after you've beaten Bethla Garrison, go to Zarghidas Trade City. There you will meet a Flower Girl who looks oddly like a flower girl in another Square game. Buy a flower from her (It's only 1 gil.)
Then head to Goug. You must have Mustadio in your traveling party. There you will find a machine which washed up on shore. You don't have the right Zodiac stone yet, so it won't open. How do you get it? Go to Goland Coal City, and go to the bar. Look at the rumor named "Ghost of Colliery."
Then go to Lesalia Imperial Capital. Before you do, kick everyone out of your party whose levels are very low. You'll need the space. In Lesalia, you'll meet up with Beowulf, a very powerful addition to your party. If you're using Agrias still, you can stop and replace her with Beowulf, he's much more powerful.
Now, you'll notice, Goland is marked as a battle. Get ready to fight and enter. There are several battles inside. After winning these 4 battles, Beowulf and Reis will ask to join. If you would like to get Cloud, say yes to both of them. Beowulf is a good addition to your party.
Now go back to Goug. There, after a comical scene, the contraption which washed up on shore will become a robot, named Worker 8. He's useful because his faith is 0. I wonder why that would be helpful? :) He's also very powerful. You don't have to use him, but you do have to take him into your party to get Cloud.
When you leave Goug, Besrodio will tell you he found a strange machine with a Cancer Zodiac symbol on it. You don't have Cancer, do you? Well, here's how to get it: go to Zeltennia Castle. Enter the bar and read the rumor titled, "Cursed Island, Nelveska." When you leave Zeltennia, a path will appear to the island. If you bought the flower from Aeris at Zarghidas, then you'll be able to fight there. So, fight. :)
After the battle, Reis will revert from her dragon form to her human form. You discover she's Beowulf's love. You have the option of taking her. Well, if you don't, you can't get Cloud. :)
When you get to Goug, the stone brings the machine to life. Well, it seems this machine is a time machine. And guess who pops out, but our old buddy Cloud! He'll run away in search of Sephiroth. To where? But Zarghidas Free City, of course, where you met Aeris.
After you get Cloud, he's level 1. You can build him up quickly to about 40 (1 hit and he gains 100 exp) If you want to use his Limit skill, you have to get the Materia Blade. Where is it? Bervenia Volcano, on top of the tallest stone pillar. You have to have someone with Move - Get Item (Chemist skill) and a Jump of at least 4. That's it. Have fun!