EN Tryout List
From A3! Wiki
All the limited and premium tryouts that have been available in the A3! English server thus far. Tryouts are also commonly referred to as scouts or gacha. For rates and more details, see Scouting, though note that the terms and some info listed there are exclusive to the JP server.
See Revival Tryouts (EN server) for the list of past tryouts that have been brought back before.
See Revival Token Tryouts (EN server) for the tryouts which require Revival Tokens instead of Gems.