All of those, plus "smart grid" stuff to get better control over demand, plus Power to Gas (electricity to methane) and gas turbines (very inefficient, but existing infrastructure can store huge amounts of energy, and efficiency isn't the primary concern for the exceptional case).

Build enough batteries and hydro to last for a few hours to a few days and use power-to-gas for longer periods of low generation (e.g. winter and no wind). There is already infrastructure in place for strategic gas reserves. We just need to build additional gas plants to meet demand when wind and solar are at production minimums.