After searching around for a bit, i found a few things to do using the cheat engine to obtain some previously unobtainable characters:
--------------------
Temporary new units (Only works on party slots, unable to re-locate or equip properly):
-Search for the number when said character is in a party slot.
-Remove the character from the slot (leave the slot empty) then search for 0.
-Find the code, then change the ID to whatever you want.
-Update/switch screens (For example, from arrange to hire) to refresh the screen.
Note:
Duplicate units usually only persist for one battle, then they dissapear.
Unit codes amongst 10-990 are hireable units, while 2010-2200 are commander units.
Units are separated in values of 10, whereas alternate or stronger forms are in values of 1.
This method can be used to find character ID's.
Choosing an invalid ID number will result in a crash.
--------------------
Hireable Commanders:
By using the same IDs above, but applied in a different way, you can obtain commander units in the slots of hireable units.
-Start by locating the hireable unit ID of your choice using the situation above.
-Search in Cheat engine for the value 0.
-Proceed to hire a unit.
-Search again on cheat engine for the value of the unit's ID.
-Find the address, the change the value to whatever ID you want.
-The slot of the old unit in the character select screen is now of the unit ID you have chosen.
Notes:
You can hire and fire units again and again to obtain more units. Duplicate units obtained this way will not work properly at all.
The only way they can be dismissed is by setting the code of the slot they are in to 0 again. (The slot will be empty but can be fixed by hiring/firing a unit)
Sometimes when using such units, the will appear as avaliable in the select unit screen, even though they are already in the party.
--------------------
Examples of Commanders IDs:
2010 = (Commander) Loki (Neutral)
2011 = (Commander) Loki (Good)
2020 = (Commander) Hvedrung
2021 = (Commander) Hvedrung (Enhanced)
2030 = (Commander) Fena
2040 = (Commander) Garm
2050 = (Commander) Tyrca (Good)
2051 = (Commander) Tyrca (Evil)
2052 = (Commander) Tyrca (Plant)
2060 = (Commander) Freya (Good)
2061 = (Commander) Freya (Evil)
2062 = (Commander) Freya (Snake)
2070 = (Commander) Thor (Good)
2071 = (Commander) Thor (Evil)
2072 = (Commander) Thor (Oni)
2072 = (Commander) Thor (Bride)
2080 = (Commander) Rigret (Good)
2081 = (Commander) Rigret (Evil)
2082 = (Commander) Rigret (Puppet)
2082 = (Commander) Rigret (Winter)
2090 = (Commander) Odin (Good)
2091 = (Commander) Odin (Evil)
2092 = (Commander) Odin (True)
2093 = (Commander) Odin (Absolute)
2094 = (Commander) Odin (Delusional)
2100 = (Commander) Ymir
2110 = (Commander) Hel
2120 = (Commander) Fenrir
2130 = (Commander) Jorm
2140 = (Commander) Menia
2150 = (Commander) Surt (Neutral)
2160 = (Commander) Farba
2170 = (Commander) Sinmara
2171 = (Commander) Sinmara (Enhanced)
2180 = (Commander) Disir
2190 = (Commander) Surt (Infernal Emperor)
2200 = (Commander) Nidhogg (Secret)
--------------------
WARNING: Crashes are to be expected. Proceed with caution, and make Backups, just in case. This is quite experimental. Good luck and have fun.