What happens if you use the shareware wad, and try an e1 pwad that has a cyber/spider

Not that such a thing would exist, but would the enemy just not be there? Would the port crash?

I think the shareware wad just locks e2 and e3 but the textures and enemies are there.

No source port is supposed to allow you to use PWADs with the shareware IWAD - there is a check in the code that detects if it's the shareware IWAD and stops it from loading a PWAD at all, and disabling this check is highly frowned upon.

If you disabled this, it would probably just crash while trying to load because it couldn't find the necessary resources.

MinerOfWorlds said:

I think the shareware wad just locks e2 and e3 but the textures and enemies are there.

Nope, most things and textures simply don't exist in the shareware IWAD. Loading a random Doom PWAD with the shareware IWAD (in the few ports that will allow it) will result in missing sprite/texture errors during level loading,

And no I'm not talking about some obscure ports: ZDoom and prBoom+ allowed it until a few years ago, and even an editor (Doom Builder) allowed you to use the shareware as a reference IWAD.

here's an old post I made on the subject