Exterior

Attempt to enter the pyramid-shaped building; two guards will approach.

Speak with the guards; one will notice your Snag Machine and ask about television appearances.

Answer "Yes" to their question to provoke a hostile reaction, leading to Gonzap and Wakin intervening, allowing you to enter the Cipher Key Lair undetected.

On the 1st Floor (1F), battle Cipher Peon Ibsol, who uses L30 Plusle, L30 Dustox, L31 Xatu, and L30 Volbeat.

In the production room on 1F, find a chest containing 3 Hyper Potions.

Go southwest from the production room to encounter Ibsol.

Head northwest and descend the staircase to find Kollo.

On the Basement 1 Floor (B1), battle Cipher Peon Kollo, who uses L31 Clamperl, L31 Octillery, L31 Lanturn, and L32 Relicanth.

Pick up TM24 (Thunderbolt) on B1.

Return to 1F and go southeast to encounter Grezle.

Battle Cipher Peon Grezle, who uses L30 Minun, L30 Beautifly, L28 Ledian, and L31 Illumise.

Head north on 1F towards a staircase to encounter Humah.

Battle Cipher Peon Humah, who uses L29 Seviper, L29 Murkrow, L28+ Paras (S), and L28+ Growlithe (S). Note that most Cipher members from this point will have more than one Shadow Pokémon.

Ascend the staircase and use the Healing Machine.

Head south and then right to find a staircase guarded by Gorog.

On the 2nd Floor (2F), battle Cipher Peon Gorog, who uses L29+ Shellder (S), L29 Rhyhorn, L29 Swalot, L29 Golbat, and L30 Sharpedo.

Take the staircase up to the 3rd Floor (3F).

Push crates onto the moon and sun-themed mosaics to unlock their respective doors.

Opening the sun door grants access to a staircase guarded by Lok.

On the 3rd Floor (3F), battle Cipher Peon Lok, who uses L30+ Beedrill (S), L30 Furret, L31 Togetic, and L30+ Pidgeotto (S).

Head up the staircase and go left to encounter Kleto.

On the 4th Floor (4F), battle Cipher Peon Kleto, who uses L30 Absol, L31 Smeargle, L30 Donphan, L31 Ampharos, and L31 Tentacruel.

Go northwest on 4F to find Flipis.

Battle Cipher Peon Flipis, who uses L31 Chimecho, L30 Kecleon, L30 Noctowl, and L29 Mightyena.

Walk right down a hall to encounter Targ.

Battle Cipher Peon Targ, who uses L30 Ninetales, L30 Jumpluff, L32 Azumarill, L30+ Tangela (S), and L30+ Butterfree (S).

Ignore the staircase at the hall's end for now and go south instead.

Battle Cipher R&D Hospel, who uses L30 Ariados, L29 Girafarig, L31 Vileplume, L31 Stantler, and L31 Granbull.

Battle Cipher Peon Snidle, who uses L31 Shedinja, L30 Wobbuffet, L35 Vibrava, and L30+ Magneton (S). Be cautious of Snidle's Wobbuffet, which can use Counter and Mirror Coat; a Dark-type Pokémon with special moves is recommended to bypass Mirror Coat's effect.

Obtain the System Lever from the white table.

Return to the staircase you ignored earlier and head up to find yourself on the roof.

Fudler is located a little to the left on the roof.