Name must be spelled exactly like an actual US President.

So far l have:
Gary Carter - Catcher
Randy Bush - First
Davey Johnson - 2nd
UL Washington - SS
Howard Johnson - 3rd
Joe Jackson - Outfield
Hack Wilson - Outfield
Reggie Jackson - Outfield

Randy Johnson - Lefty
Whitey Ford - Lefty
Don Wilson - Righty

I am sure there are better choices - these are off the top of my head - give it a shot

Walter Johnson
Claudell Washington
Grover Cleveland Alexander ?

Ted williams, first base
Bob Gibson rt p
sandy koufax lt p
willie mays center
ossie smith ss
Hank Aaron left
Stan Musual right
pete Rose third
Johnney Bench Catcher
can not think of a second baseman , but those are my choices Rock

idk how much more you could do but of course your coach could be Ron Washington also haha and wth is the other guy above me talking about

Here is one for your bench:
William McKinley ''Max'' Venable http://baseball-reference.com/v/venabma01.shtml

And one for the bullpen:
Franklin Delano Roosevelt ''Ted'' Wieand http://baseball-reference.com/w/wieante01.shtml

For catcher, you could have John Kennedy. Yes, the exact same name as the president. Does not get much better than that.