I have been asked several times recently on how to adjust the font size on analytic charts and grids. Within the dashboard designer you have this ability although it is not always exposed automatically when editing/creating charts and grids.
When first creating an analytic chart/grid you are presented with the Analytic View Designer in the workspace area of the Dashboard Designer. Unfortunately, the Home tab remains selected in the Dashboard Designer - leaving the editing capabilities hidden from the user initially. If you select the Edit tab in the Dashboard Designer you will see the edit toolbar appear with the many editing capabilities easily exposed in the Dashboard Designer.
From here, you can easily adjust font sizes, change numerical formatting of the chart/grid, adjust the report type, report layout (grid), control legend placement (chart) and adjust the row and column label length (view options - grid).
Alyson Powell Erwin