Unown are very mysterious. They use an attack called Hidden Power and it varies among the Pokémon that uses it. Here's how it works:

Unown is a Psychic type, correct? List some of the types it's weak against. Well, there's bug and dark. If Unown uses Hidden Power against them, Hidden Power will be Super Effective. Hidden Power is an attack that attacks the opponent that the user is weak against. Of course, there's more to this "opposite" attack. Let's say that Unown hits a Psychic type. This will not be effective. If Unown hits any other type, that doesn't matter if psychic is just a plain attack, ex. Normal, Fire, Water... You get the idea.

Now onto the Ruins of Alph. There are 4 puzzles you must solve. Fortunately, I'm here to give you the answers! Here are the answers to Kabuto, Ho-oh, Aerodactyl, and Omanyte:

Is that good? Well, there's a little more to these puzzles. Each time you solved a puzzle, more kinds if Unown will appear. What are these kinds you ask? Here they are!

Now how do you like those? If you capture 3 of them, a Professor will come and give you an Unowndex. You will get a message each time you capture a different Unown in your new Unowndex. I'll be getting the messages someday, I haven't even caught 10 yet!