I think it has some built-in cheats.

And to know I could have thought that up myself, but didnt 😁 (thanks)

But I still want to know why these trainers dont work, and if this is something dosbox related. Might affect other games too.

Right I think I found it: 😁

So, there is thing called a scene-release, which is the first 100% cracked release of a game.
Most trainers are bound to this release unless otherwise stated. All scene groups follow these rules.
Its a bit like the 'pirate code' from that pirates of the Caribbean movie.
The Code is more what you'd call "guidelines" than actual rules.Welcome aboard the Black Pearl, Miss Turner.

So if you have a different version, there is a big chance most trainers WONT work.
And I can say for a 100% that my game is NOT a scene release. 😒

I think I solved this, but I am not really sure, any thoughts ?

I have the CD-ROM version of this game but can't get it to run in DOSBox. The screen just goes black when I run ZOOL2.EXE. Does anyone know if the game is compatible?

Try setting machine=vgaonly in DOSBox conf.

That worked, thank you.

Hooray, I found the solution. So here goes:

There is a 100% fully functional beta release by the scene and most of the trainers were written for that version. It can be identified it by: ZOOL2.DAT 1325150 bytes, timestamp: may 24 1994 . These trainers work:

1. DODZ2T+4.EXE
2. DRD-Z2TRN.COM
3. LGNDZ2TR.EXE
4. NW-Z2TR.EXE
5. TRSIZ2TR.EXE

The retail release can be identified by: ZOOL2.DAT 1326654 bytes, timestamp jun 28 1994. This trainer works:

1. PTG-Z2TR.EXE (I needed this one, and should have pressed 0-9 to activate, ha!)

Problem solved!