Putting Trinexx in other rooms isn't working

When I place all the stuff that's normally in Trinexx's boss room somewhere else, it fails to work properly.

This is what's copied over from the original room:

Room header (Including effect "04")
Shell
BG2: On Top
Trinexx1, Trinexx2, Trinexx3 all placed together in the same spot in reference of shell
Blockset
Enemy Graphics Sheet


Is there a way of fixing this using ASM or hex editing (or even in HM)?

Well it worked for me. In the IQ hack I've put Trinexx in room 226 and it worked normally.

Layout is 0, BG2 is On top (for the shell), blockset is 13, PAL is 25, Enemy BLK is 23, effect is 04, TAG1 is (in my case) clear to open (since semiboss), TAG2 (kill boss again) to not drop a container since semiboss.

Then insert element FF2 (ie Trinexx shell) while having the number 2 checked in HM (ie inserting shell on layer2, which then together with BG2 on top will make it walk-through). So shell is just decoration.

Then insert 3 sprites: Trinexx 1, 2, 3, which is for all 3 heads. I even managed to make a Trinexx with one primary head and 2 fire heads and 2 ice heads. But this is too much sprites for CPU to handle thus slowdowns occured. But you can make a Trinexx with one primary head, one ice and 2 fire heads with no slowdowns.

So I really don't know where you have problems.

Also do note, if this is your final boss (and not a semiboss) of the dungeon, then it is best to insert him in any already existing final-boss-rooms, since otherwise you might have problems, if you don't redefine the boss room, to (you know) drop the crytal and go into dungeon-finished stuff like talk to maiden and swing sword and spawn you back at the exit, which is further editing, but even this can be done.

I found out the problem, the heads were layered incorrectly. Trinexx's heads are meant to be placed in a certain order, first the main head, then the ice head, and finally the fire head (all of course on layer 1). If any one of the heads were not placed in the correct order, the entire fight breaks.