Well i’ll add on to that, because it’s true to an extent. Creatine (depending on which product - My favorite being creadrive and cytogainer) will give you that quick 10 pounds you may be looking for, but you will quickly piss 5-8 of those pounds away.
Creatine will not magically make you stronger just by taking it, what it does however is “supplements you” during your workout.
The best way to explain it is to say that creatine helps your muscles build muscle.
Creatine helps retain water, and your muscles, they are in an optimal state for building new muscle. As a result, when you take creatine and water is retained in your muscles then when you weight train you will get more of an effect because your muscles are better capable of building muscle.
So you become more efficient as a lifter.
As for dehydration - the creatine is retaining your water so its something you need to watch, and make sure you drink plenty of water before during and after.