I didn't think sponsorship was related to being one of the founding airlines. However, the founding airlines tend to be the larger carriers within OW and thus have the resources to sponsor a new member with regards to Pilot, FA, and IT standards.

AA has their Flagship University(which is awesome), and BA has a huge training center at Heathrow that is used by other airlines around the world.

AA Flagship University (more here)
BA Training Center
Cathay Pacific Training