Alstom is bidding on their own, with an AGV variant.
Bombardier and Hitachi both bid individually but then combined their bids, and were progressing with a derivative of the ETR 1000 Frecciarossa, which Hitachi had involvement with as a result of their Ansaldo-Breda purchase, it wasn't strictly a Hitachi product though I understand it was gaining more Hitachi designed, Japanese origin Shinkansen technology. Bombardier's stake in the joint-venture is currently offered for sale, Hitachi have first refusal but potentially another manufacturer could purchase that stake - perhaps one of Hitachi's Japanese collaborators, such as J-TREC/J-TEC or Kawasaki Heavy Industries.
Siemens were offering the Velaro which everybody knows and loves from Eurostar e320.
The Spanish comedy double act of Talgo and CAF round out the five bidders. Talgo were offering the death trap Avril platform, which scares the **** out of me with those independent wheeled bogieless carriages. CAF were drafted in to ensure dreadful reliability, woeful delivery timescales and atrocious build quality were still on offer after Bombardier decided to involve themselves with Hitachi.