Cloud Strife is easily the most iconic Final Fantasy character and he has appeared in numerous crossovers in other games, including Puzzle & Dragons and Super Smash Bros. Ultimate, but he was appearing in other Squaresoft games all the way back in the days of the PlayStation, as was the case with Final Fantasy Tactics.
Final Fantasy VII was released in Japan in January 1997, while Final Fantasy Tactics was released in June of the same year. Cloud is a secret character that can be recruited in Final Fantasy Tactics, so long as the player keeps Mustadio in their party and doesn't let him permanently die. Once the player reaches Chapter 4, they can visit the Clockwork City of Goug and complete a quest involving the Construct 8 robot. If the player recruits Beowulf and saves Reis, they will be given another piece of auracite, which can be given to Mustadio's father in order to summon Cloud using a piece of ancient technology.
It's implied that Cloud was summoned to Ivalice during the time in Final Fantasy VII when he is trapped in the Lifestream during the destruction of Mideel. As such, his memories are messed up and he runs off, leaving Ramza to save him. Cloud encounters a flower girl who just happens to be called Aerith, and Ramza & company need to save them from thugs.
Cloud is one of the strongest party members in Final Fantasy VII, but he's a wimp in Ivalice. The player gets him at a fairly late point in the game, at which point they will already have a number of high-level generic characters with maxed-out jobs and story characters with unique powers. The player also needs to go on an annoying quest to find a compatible weapon that will allow Cloud to use his unique Limit Break command and the hassle isn't worth it for most players, especially as Final Fantasy Tactics becomes a cakewalk after Riovanes Castle.
Cloud does have a few unique assets that might make a player interested in him, or at least he did in the original version of Final Fantasy Tactics. Cloud was the only male character in the game who could equip a Ribbon, which blocked all status effects and was easily the best accessory in the game, but it was restricted to female characters. The fact that Cloud could wear the Ribbon was a reference to the cross-dressing quest in Final Fantasy VII. The updated War of the Lions version of Final Fantasy Tactics made it possible for Onion Knights to equip the Ribbon, so Cloud lost his unique attribute.
Cloud's appearance in Final Fantasy Tactics is strange. His role in the story is minor and can be missed, it's generally not worth the effort it takes to bring him up to the same level as the other party members in the game, and it's never explained how he returned to his homeworld. Then again, it was never explained how Ramza escaped from the battle against Ultima either, so it can fan theory-waved away by saying that the auracite sent them back to their homeworlds. Cloud would go on to have many appearances in other Final Fantasy games, Squaresoft/Square Enix games, and games released by other companies, so it's a shame that his first major crossover was so forgettable.