The whole main purpose of this beta would be to test out the online net code, and Capcom certainly takes this particular matter very seriously. Apparently, all data that Capcom picked up from this particular beta will eventually be used to improve the net code in the final product.
The entire beta run will see all of the half dozen characters be made available, in other words, players can give all of those characters shown off at E3 in the E3 build a spin. Four characters that are playable will be made available right from the get go, while Birdie and Cammy will only become playable this coming Saturday, July 25th. The delayed release for these two characters are due to net code testing, as well as giving their new content delivery system a try. [Press Release]