You say that "a lot of titans lost to some gods". This simply isn't true. The gods weren't capable of defeating the titans alone; they were only able to with help from the Cyclopses and the primordial giants.
It's also worth mentioning that there was a prophecy that Rhea and Chronos were doomed to be overthrown by their children. So they were hardly defeated by the gods - the gods were destined to win before they were even born.
Titans are an older generation of gods and these are specified by being weaker than the new generation of gods.
As you said the gods were destined to win.
I want to say something about demi-gods too.
Demi-god is some made by a god and a human or you can be a human and become a demi-god yourself by being chosen to be one and after you can become a god.
The most powerful god is Zeus.
The fastest god is Hermes.
And more and more...
The point is the titans are the fathers and mothers of the gods themselves. And titans were destined to be defeated even Kronos checked after their born if they were a titan or a god.
Gods were helped by cyclopses and giants that true but you didn't specify that their souls were absorbed so Hades became stronger.
Only gods to match Hades's strength were Zeus and Poseidon.
And the cyclopses and giants sided with titans they didn't side with gods. Hades absorbed their souls with the help of Poseidon and Zeus struck a lightning and he used the blade of Olympus to unleash the great power so Zeus could ban the Titans to Tartarus.
