Want to cut a grooves in plywood sub floor with some kind of tool
The best tool that can be used to cut grooves in plywood sub floor is a circular saw. The saw is good as it is easy to use and cuts the grooves in the desired sizes. Check out http://www.ehow.com/how_8559051_put-down-tongue-groove-subfloor.html for more details.
You can set the depth of your circular saw to cut grooves at what ever depth that you want. I am curious though, as to why you want to cut grooves in the subfloor.
A table saw, router, or rabbet plane will be much more accurate than a circular saw, but if that's all you have it will work.
Table saw with a dado head. But if you don't have a table saw a router after laying out the lines and clamping down a piece of milled stock as a straight line guide is ok.
Buy tongue-in-groove plywood.