(Dehacked/Vanilla) How to make player/player's weapons use enemy and other things' sounds?

I don't think you can use monster code pointers for weapon frames and vice versa.   Even in decorate there seems to be player weapon and monster versions of similar code pointer-like functions.

In the old days people just replaced player weapon sounds.   So you may just have to juggle around the code pointer frames with OpenShotgun2, LoadShotgun2, CloseShotgun2, and BFGSound.   And replace the appropriate DS* sounds in a wad.   Or in the Text/Strings section, rename those sounds to the same as the monster sounds you want to use, such as manatk.   Also the BFG Shot/Projectile itself has no "alert" sound for it shooting and can be given one.

I thought of a way to free up two player weapon sounds without really sacrificing anything of the Super Shotgun or BFG.   Extract dsdbopn, dsdbload, and dsdbcls from doom2.wad.   Open them in an audio editor such as Audacity. 

Paste dbload and dbcls after dbopn, with the appropriate fraction of a second of silence in between each if any.  

Maybe you can mathematically put the right amount of silence.
The frame with the open sound has duration 7 + the next frame is 7.
So Load starts playing 14/35 of a second after Opn starts playing.
You'll have to subtract the length of the Opn sound from 14/35 of a second.
Then Cls starts playing 13/35 sec after Load starts playing.
So subtract the length of Cls from 13/35 of a sec.

Or you can just experiment through trial and error how much silence to have.

You might not need any, and the three sounds pasted consecutively may be fine.

Or you lower duration of a SSG frames or two by 1 maybe, though that makes the nastiest

close range deathmatch weapon even more overpowered. 

Then insert your new combined triple sound in dsdbopn in a pwad.
In Dehacked/Whacked, substitute two frames with no code pointer
for the frames that play dbload and dbcls.

Now change dbload and dbcls to whatever you want since you've freed them
up for use in other weapons.

EDIT: It has occurred to me that the sounds may be longer than they're given time to play, so you may have mix-paste, cut a couple short, or lengthen frame durations for them to sync up perfectly.