you could put /usr/local/bin/ at the beginning of PATH
might break other things..
better solution .. try ggrep , if nothing then create a symlink in /usr/local/bin/
ln -s grep /usr/local/bin/ggrep
and make sure /usr/local/bin/ is in PATH ( towards end )
you just have to remember to use ggrep
never used solaris, but I assume you can use alias
depends if there is anything very special about solaris's grep, that could also cause problems