The original glitch was that if you swapped out your digijacks with an enemy, they would spawn as your allegiance. You would be able to take that NPC anywhere and load it into any map you wanted because the digijacks are constant.

You will need Borderlands Pre-Sequel Cheat Compilation by Technojacker to use the Enemy Swapper: https://www.dropbox.com/sh/v2kg4nh9cfndq58/AAAjIOCO2JJGtPORmJxRIaVea?dl=0

Here's JoltzDude139's video on it;

The reason the original glitch worked was because the digijacks were a constant. I had assumed those were the only constants but I recently discovered that some enemies can generate constants as well. (A list of the NPCs I have found will be given later)

When you replace your digijacks with one of the aforementioned enemies and leave the area, some other enemy resources will load into the other maps as well that will become constants as long as the enemy you swapped out remains in a constant slot. These enemy slots I will call Spawnslots.

All you need to do is replace a digijack with one of the enemies and then go to a map that houses an enemy you want, then replace the extra Spawnslots that came with the enemy you originaly swapped out with the enemy you want to make a constant. This allows you to chain together many spawnslots to take a wide range of enemies with you to other levels, allowing you to construct elaborate sequences where different enemies spawn.

I used this to create a Boss Rush. It was my first attempt at the idea so it is a little chaotic.

Here is a list of some enemies that add Spawnslots.

Syntax:

Name: (Parent NPC)
Found In Maps: Map, Map 2
Map Code Names: Map_P, Map_P2
NPC Code Name: Population Defininition; Pawn Balance
Total Spawnslots: 3 (Doesn't include the NPC Code Name which is technically a Spawnslot)
Used: 3 (Spawnslots that are spawned by the Parent NPC)
* Population Definition 1;
- Pawn Balance 1
- Pawn Balance 2
* Population Definition 2; Pawn Balance 3
Free: 0 (Spawnslots that aren't spawned by the Parent NPC but might spawn in certain maps naturally)

Spawnslot NPCs:

Opha Superior:
Found in Maps: Elseer
Map Code Names: InnerCore_P
NPC Code Name: PopDef_Eridian_OphaBoss; PawnBalance_OphaBoss
Total Spawnslots: 12
Used: 7
* PopDef_Putti;
- PawnBalance_Putti_Corrosive
- PawnBalance_Putti_Cryo
- PawnBalance_Putti_Fire
- PawnBalance_Putti_Normal
- PawnBalance_Putti_Shock
* PopDef_Guardian_Cheru; PawnBalance_Guardian_Cheru
* PopDef_Sera_Guardian; PawnBalance_Sera_Guardian
Free: 5
* Popdef_Putti_Normal; PawnBalance_Putti_Normal
* Popdef_Putti_Cryo; PawnBalance_Putti_Cryo
* Popdef_Putti_Fire; PawnBalance_Putti_Fire
* Popdef_Putti_Corrosive; PawnBalance_Putti_Corrosive
* Popdef_Putti_Shock; PawnBalance_Putti_Shock

Iwajira:
Found in Maps: Serenity's Waste
Map Code Names: Moonsurface_P
NPC Code Name: PopDef_Rockzilla; PawnBalance_Rockzilla
Total Spawnslots: 9
Used: 2
* PopDef_Kraggon_SpawnProxy; PawnBalance_Kraggon_SpawnProxy
* PopDef_KragonPup_RockSpawn; PawnBalance_ElementalBeastie
Free: 7
* PopDef_GrandsonFlamey; PawnBalance_GrandsonFlamey
* PopDef_ElementalSpitter; PawnBalance_ElementalSpitter
* PopDef_ElementalCharger; PawnBalance_ElementalCharger
* PopDef_FrostBeast_Small; PawnBalance_Frostbeast_Small
* PopDef_FrostBeast_Mini; PawnBalance_Frostbeast_Mini
* PopDef_ElementalMama; PawnBalance_ElementalMama
* PopDef_ElementalBeast; PawnBalance_ElementalBeast


Felicity Rampant:
Found in Maps: Titan Robot Production Plant
Map Code Names: DahlFactory_Boss
NPC Code Name: PopDef_ProtoWarBot_CoreBody; PawnBalance_ProtoWarBot_CoreBody
Total Spawnslots: 7
Used: 5
* PopDef_ProtoWarBot_BlastTurret; Pawn_Balance_ProtoWarBot_BlastTurret
* PopDef_ProtoWarBot_RocketTurret; Pawn_Balance_ProtoWarBot_RocketTurret
* PopDef_ProtoWarBot_GunLoader; PawnBalance_ProtoWarBot_GunLoader
* PopDef_ProtoWarBot_ShieldDrone; PawnBalance_ProtoWarBot_ShieldDrone
* PopDef_RepairDrone; PawnBalance_RepairDrone
Free: 2
* PopDef_ProtoWarBot_FriendLoaderYellow; PawnBalance_ProtoWarBot_FriendLoaderYellow
* PopDef_ProtoWarBot_FriendLoader; PawnBalance_ProtoWarBot_FriendLoader

Spectral Shuggurath:
Found in Maps: Triton Flats
Map Code Names: Moon_P
NPC Code Name: PopDef_HiveFlyers_Station_TritonFlats; PawnBalance_HiveMind
Total Spawnslots: 4
Used: 1
* PopulationDef_HiveMindRodunk; PawnBalance_HiveMindRodunk
Free: 3
* PopDef_HiveFlyers_Station_TritonFlats; PawnBalance_HiveFlyer
* PopDef_RodunkMix;
- PawnBalance_Rodunk
- Pawnbalance_Brodunk

Tork Empress:
Found in Maps: Research and Development, Titan Production Facility, Stanton's Liver, Outlands Canyon
Map Code Names: RandDFacility_P, DahlFactory_P, StantonsLiver_P, Outlands_P2
NPC Code Name: PopDef_TorkQueen; PawnBalance_TorkQueen
Total Spawnslots: 2
Used: 2
* PopDef_TorkSwarmling; PawnBalance_TorkSwarmling
* PopDef_Tork; PawnBalance_Tork
Free: 0

Meg:
Found in Maps: Hyperion Hub of Heroism
Map Code Names: CentralTerminal_P
NPC Code Name: PopDef_Thresher_Meg; PawnBalance_Thresher_Meg
Total Spawnslots: 2
Used: 2
* PopDef_Tentacle_Meg; PawnBalance_Tentacle_Meg
* PopDef_Tentacle_Meg_B; PawnBalance_Tentacle_Meg_B
Free: 0

Outcast:
Found in Maps: Stanton's Liver, Outlands Canyon
Map Code Names: StantonsLiver_P, Outlands_P2
NPC Code Name: PopDef_ScavWastelandWalker; PawnBalance_ScavWastelandWalker
Total Spawnslots: 1
Used: 1
* PopDef_Blowfly; PawnBalance_Blowfly
Free: 0