DoomGaze

Based on my reading of the code, all five would have their HP set from the Doomgaze HP variable, but only the last one would write its HP back when the battle ended. The next time you started the battle, they would all get the HP of that last Doomgaze.
This is because the game sets a variable at the beginning of battle to which monster is Doomgaze. But with only one variable, each Doomgaze simply overwrites the values stored by the previous ones.
Also, it doesn't look like it would matter which enemies you included in the battle, they will ALL have their HP set to the same as Doomgaze because the HP setting is only based on the formation number; The game thinks ANY monster in Doomgaze's formation must be Doomgaze.