This script writes one OBJ for all selected polygons for each of 24 frames.

/////////////////////////
//select all geometry, which happened to be
//named Poly_* (Poly1 - Poly15 in this example)

for ($i =1; $i <= 15 ; $i++){
select -tgl ("poly_" + $i);
}

// export to obj

for( $index = 0; $index <= 24; $index++ )
   {
   	currentTime $index;

file -op "groups=0;ptgroups=0;materials=0;smoothing=0;normals=0" -typ
"OBJexport" -pr -es ("PATH_TO_TARGET_DIR/objExported." + $index);
   }
/////////////////////

This code scales a character’s top node, called “whole” here, before exporting the geometry, then rescales it. The result are objs scaled as specified.

/////////////////////////
//scale Character
setAttr "whole.scaleX" 3;
setAttr "whole.scaleY" 3;
setAttr "whole.scaleZ" 3;

//select all geometry, which happened to be
//named Poly_* (Poly1 - Poly15 in this example)

for ($i =1; $i <= 15 ; $i++){

select -tgl ("poly_" + $i);
}

// export to obj
for( $index = 0; $index <= 24; $index++ )
   {
   	currentTime $index;
file -op "groups=0;ptgroups=0;materials=0;smoothing=0;normals=0" -typ
"OBJexport" -pr -es ("PATH_TO_TARGET_DIR/objExported." + $index);
   }
//rescale
setAttr "whole.scaleX" 1;
setAttr "whole.scaleY" 1;
setAttr "whole.scaleZ" 1;
/////////////////////