When I first read the title, I thought you meant that you wanted to get 255 of every stat for all character which can only be achieved by using Clear Spheres on many nodes of the Sphere Grid and replacing them, since the regular Sphere Grid can't max out all stats I believe.

Anyways, Overdrive -> AP is gotten from Door to Tomorrow x30. Wings to Discovery are for Break HP Limit.

I remember two ways to get them:
1. Open a certain number of chests during the Remiem Chocobo Race and win.

2. Bribe Ultima Weapon in the Omega Ruins for about 1 million gil. This gets you 99 of them.