On the first floor of the Celestial Tower, you'll find Professor Juniper. Talk to her and she'll give you the Lucky Egg — a valuable held item that increases the amount of EXP you earn by 50%! It's a staple for training and is particularly handy when fighting against Audino.
Go ahead and climb up the stairs to the tower to reach the next floor.
Celestial Tower 2F
|Celestial Tower 2F|
|Litwick||/||Lv. 27 ~ 30||100%|
The first Trainer you'll fight up here is a Psychic, and she uses a Musharna L36. To the left of her and up a bit is a Hyper Potion.
Head on over to the right now and fight the School Girl who uses a Litwick L35. Right next to her is TM61 (Will-O-Wisp), which burns the foe when used. It's handy for Pokemon with Hex or just to lower the foe's Attack stat by half.
Lastly on this floor is a Pokefan ♂, using a Clefairy L35. Take him down, then climb up the stairs to the next floor.
Celestial Tower 3F
|Celestial Tower 3F|
|Litwick||/||Lv. 28 ~ 31||80%|
|Elgyem||Lv. 30 ~ 31||15%|
Go on and fight the Pokefan ♀ right near the entrance. She uses a Cubchoo L35. There's a Psychic right beneath her who uses an Espeon L36. Just past him is a Revive. Alright, now go back east and fight the other Psychic; this one uses an Elgyem L35 and a Duosion L35.
Now, just south of all of the action, there's a Nurse you can talk to. She'll heal up your Pokemon, but only if you beat her in a battle, first! She uses a Leavanny L35. Definitely fight her, because healing up your Pokemon is pretty nice.
Alright, head up the stairs to the fourth floor now.
Celestial Tower 4F
|Celestial Tower 4F|
|Litwick||/||Lv. 29 ~ 32||65%|
|Elgyem||Lv. 30 ~ 32||25%|
To the west of the entrance is a Socialite, and she uses a Roselia L35. She gives a ton of money after you beat her, so equipping an Amulet Coin is a good idea. Just past her is a PP Up, and then you can head east to fight a Gentleman, who gives a similar amount of cash when you beat him. He's got an Umbreon L35, though.
Head on over and fight the Psychic nearby, who's got a Yamask L35 and a Gothorita L35. Right by the Psychic is TM65 (Shadow Claw), which is a fairly decent Ghost-type attack with 70 power that has a high chance of a critical hit. A lot of non-Ghost-type Pokemon can learn it, though, and it's good against Psychic- and Ghost-type Pokemon, making it a fairly appealing option.
Alright, now head up the stairs and reach the top of the tower!
Celestial Tower 5F (Top)
|Celestial Tower 5F|
|Litwick||/||Lv. 30 ~ 33||40%|
|Elgyem||Lv. 30 ~ 33||40%|
There's a Ghost Gem hiding over on the west side of the bell. Otherwise, ring the bell while you're up here. Why not, right?
Alright, now that you've done that, go on and head back to Mistralton City and take on the Mistralton Gym!