From BBC World Service:

“The major arms that Saudi Arabia buys come from the US and UK. Its air force comes from primarily the US, F-15s and F-16s, but it has also purchased a large number of typhoons. The UK is a main participant in the manufacture and sale of the typhoon. It also supplies training to Saudi forces.”

Other comments on the main enablers of the war: the US and UK have helped with refueling of Saudi bombers, reinforcing the naval blockade, and under Obama the US only pulled back symbolically while still providing support.

A Saudi Air Force advanced F-15SA fighter jet performs with the Royal Saudi Hawks, the aerobatic team of the Royal Saudi Air Force, during a ceremony marking the 50th anniversary of the creation of the King Faisal Air Academy at King Salman airbase in Riyadh on January 25, 2017.

From The Aviationist:

On March 31st, the Royal Saudi Air Force flew to Sudan to train with the Sudanese. In 2015, Sudan changed their long-standing alliance with Iran to join the Saudi-led coalition fighting the Houthi rebels.