Hi Maureen,
welcome to electronicspoint.
Ideally all.
Which combinations work depends on the application.
Typically batteries are operated in series. The voltages of the single cells add up to the voltage of the whole stack. Differences in single cell voltages are comparatively unimportant, as the voltage of the whole stack counts.
The same current flows through all cells (as in every series connection), so all cells are discharged in the same way. Therefore the capacity (mAh) of all cells should match as closely as possible. The cell with the least capacity will be discharged first and has a risk of being reversely charged, the polarity may swap and the cell can be destroyed.
The series resistances of the single cells simply add up to the series resistance of the whole stack. The effect is voltage drop across the series resistance under load and heating of the cells due to power dissipation in the series resistance. There is no need to match the series resistances of the cells.
Make sure you charge the cells as single cells, not as a complete stack. This will optimize the lifetime of the batteries.
Here is useful stuff to read about batteries.