Which cmd.exe internal commands clear the ERRORLEVEL to 0 upon success?

This answer is based on experiments I ran under Windows 10. I doubt there are differences with earlier Windows versions that use cmd.exe, but it is possible.

Also note - This answer does not attempt to document the ERRORLEVEL result when an internal command encounters an error (except for a wee bit concerning DEL and ERASE)

Not only are there difference between commands, but a single command can behave differently depending on whether it was run from the command line, or within a batch script with a .bat extension, or from within a batch script with a .cmd extension.

The following set of commands never clear the ERRORLEVEL to 0 upon success, regardless of context, but instead preserve the prior ERRORLEVEL:

• BREAK
• CLS
• ECHO
• ENDLOCAL
• FOR : Obviously, commands in the DO clause may set the ERRORLEVEL, but a successful FOR with at least one iteration does not set the ERRORLEVEL to 0 on its own.
• GOTO
• IF : Obviously, commands executed by IF may set the ERRORLEVEL, but a successful IF does not set ERRORLEVEL to 0 on its own.
• KEYS
• PAUSE
• POPD
• RD
• REM
• RMDIR
• SHIFT
• START
• TITLE

The next set of commands always clear the ERRORLEVEL to 0 upon success, regardless of context:

• CD
• CHDIR
• COLOR
• COPY
• DATE
• DEL : Always clears ERRORLEVEL, even if the DEL fails (except when run without any file argument).
• DIR
• ERASE : Always clears ERRORLEVEL, even if ERASE fails. (except when run without any file argument).
• MD
• MKDIR
• MKLINK
• MOVE
• PUSHD
• REN
• RENAME
• SETLOCAL
• TIME
• TYPE
• VER
• VERIFY
• VOL

Then there are these commands that do not clear ERRORLEVEL upon success if issued from the command line or within a script with a .bat extension, but do clear the ERRORLEVEL to 0 if issued from a script with a .cmd extension. See https://stackoverflow.com/a/148991/1012053 and https://groups.google.com/forum/#!msg/microsoft.public.win2000.cmdprompt.admin/XHeUq8oe2wk/LIEViGNmkK0J for more info.

• ASSOC
• DPATH
• FTYPE
• PATH
• PROMPT
• SET

Lastly, there are these commands that do not fit neatly into any of the prior categories:

• CALL : If a :routine or batch script is CALLed, then ERRORLEVEL is exclusively controlled by the CALLed script or :routine. But any other type of successful CALL to a command will always clear ERRORLEVEL to 0 if the CALLed command does not otherwise set it.
  Example: call echo OK.

• EXIT : If used without /B, then the cmd.exe session terminates and there is no more ERRORLEVEL, just the cmd.exe return code. Obviously EXIT /B 0 clears the ERRORLEVEL to 0, but EXIT /B without a value preserves the prior ERRORLEVEL.

I believe that accounts for all internal commands, unless there is an undocumented command that I missed.

Your description of CALL command is incomplete:

CALL : Clears ERRORLEVEL if the CALLed command does not otherwise set it. Example: call echo OK.

Check this small example:

@echo off

call :setTwo
echo Set two: %errorlevel%

call :preserve
echo Preserve: %errorlevel%

call echo Reset
echo Reset: %errorlevel%

call :subNotExists 2> NUL
echo Sub not exist: %errorlevel%

goto :EOF

:setTwo
exit /B 2

:preserve
echo Preserve
exit /B

Output:

Set two: 2
Preserve
Preserve: 2
Reset
Reset: 0
Sub not exist: 1

CALL description should say something like this:

• CALL : Clears ERRORLEVEL if the CALLed command does not otherwise set it. Example: call echo OK, but if the called command is a subroutine it preserves the prior ERRORLEVEL. If the called subroutine does not exist, it sets the ERRORLEVEL to 1.