Easy actually. The unown pieces of ICE (Regice), ROCK (Regirock), and STEEL (Registeel). Regigigas is last, but you don't need any for him. You will have to fight all the regis, and with Regigigas you fight more, but Team Charm will help.
Dude, it is so simple. Get the purple stones- I, C, and E. If you look at the information on them, it will translate the Unown Language for you.
In the dungeon, sometimes a defeated Unown will drop a stone shaped like itself. You need to collect the stones that spell out "ROCK". At the non-dungeon part, check the pillar in the center and follow the instructions. The stones you collected will react with the pillar, revealing a stairway. You do the same for Ice and Steel Aegis Cave.
You need patience to get through that part. It's not that hard getting past the stones.You do need to move through the stones really fast.
You need to enter the cave with Team Charm.
If you are refering to the Aegis Cave mystery, then there is a process you must go through in order to progress to the deeper levels. You will notice that when you defeat Unown in this dungeon, some of them drop a perculiar stone which is marked with their symbol. These symbols can be translated to English letters (and the punctuation marks of ! and ?) and play an important part in the mystery of the cave. You must gather the apporpriate Unown stones which spell out the section of the cave you are in in order to move forward. If you are in the first section of Aegis Cave, then you will need to gather the Unown stones which translate to the letters 'I' 'C' and 'E'. With these in your inventory, place a hand on the notification in the base level and it will clear the path to the next chamber. Proceding to the next chamber will require you to gather the stones marked 'R' 'O' 'C' and 'K'. And lastly, gather the stones marked with 'S' 'T' 'E' 'E' and 'L' to unlock the last chamber and solve the mystery. Once you have navigated through all of the sections of the cave, you can progress in the story. However, if you are defeated in the dungeon or visit Aegis Cave again, you will need to complete the same process as before, and gather all of the Unown stones anew.
You would need 96 stones.
You have to go to Aegis Cave, But to get there you need to release manaphy into the sea and sleep for a few days and then team charm comes and takes you to Aegis Cave.
Keep defeating Unown and look at the stones they drop. Each represents a letter (you can use Info to tell you which letter it is, if it looks unclear), you need an I, a C and an E. Smart players will guess the next levels will be ROCK and STEEL so will bring along any of those stones too in readiness.
what you do is you walk over to the giant stone and you read it half way through reading it,it will show you some unown's remember the unown's and go into the cave get all the stones that match the unown's that you remembered then go to the stone and keep clicking A the some steps will come walk down the steps and you vs regice ko him and do the same thing as i told you on the next stone.
Chestnuts need small stones to get rid of the germs as the small stones are not normal stones.
Have Aegis as your guest.Ghange your dragon element to Light (or Ice) and have a good Light (or Ice) weapon. Note:Use Ice element on your dragon and on weapon only if enemy is powerful and you need to use Ice Domain(from Aegis).
You cannot buy the stones because it is only two made by G-d. It is hidden by G-d through His Priest. For Israel to stand, she will need these stones but they have to pray and trace down the real high priest blood line.