In Solaris 2.x static linking is not supported for any of the system libraries. All the functions that use /etc/nsswitch.conf (getXXXbyYYY, getpwXXX, etc) require the dynamic linker to load the code to load these functions. It is not possible to write configurable/extensible functions in such a way that dynamic linking is not required. E.g., you can add your own nsswitch.conf backend which would not be known to programs statically linked to only the standard backend code.
Programs that link statically against any of the OS libraries may not run in the next release and are not ABI compliant.
Programs that link statically don't get some dynamic performance enhancements found in the shared libraries: using hardware multiply/divide on systems that support it; using fast mem*() operations on UltraSPARC etc. And you won't pick up performance enhancements in next releases: e.g., Solaris 2.5 comes with a 4x faster fread/fwrite and the "Name Server Cache Daemon".
If you don't care about ABI compliance, i.e., you won't ship your program as a product and don't care that you may need to recompile after an OS upgrade, here are some of your options:
Link statically against all but libdl:
cc -Bstatic .... -Bdynamic -ldl -Bstatic
Link against dl* stubs (gethostbyXXX, getpwXXX etc won't work any longer):
char *dlopen() { return 0;}
int dlclose() { return 0;}
char *dlsym() { return 0;}
char *dlerror() { return "dynamic linking not loaded";}
If you don't want any dependencies on /usr, link against the dynamic libs in /etc/lib:
cc -Bstatic ... -Bdynamic -R/etc/lib -Wl,-I/etc/lib/ld.so.1 -ldl -Bstatic ....
If you still get undefined symbols, check with ldd for all your libraries if they have any dynamic dependencies. E.g.,
% ldd /usr/lib/libsocket.so.1 libnsl.so.1 => /usr/lib/libnsl.so.1 libdl.so.1 => /usr/lib/libdl.so.1 libc.so.1 => /usr/lib/libc.so.1 libintl.so.1 => /usr/lib/libintl.so.1 libw.so.1 => /usr/lib/libw.so.1
tells you that if you want to link libsocket statically, you need to link with -lnsl -ldl -lc -lintl and -lw as well.
There is no way to statically link 64 bit executables; no 64 bit archive libraries are shipped with Solaris.