The official website for Level-5 and CAPCOM's crossover game Layton-kyōju Vs Gyakuten Saiban (Professor Layton vs. Ace Attorney) announced the game's voice cast on Friday. Yo Oizumi (Brave Story, Howl's Moving Castle) and Maki Horikita (Densha Otoko series, Always: Sunset on Third Street) will reprise their respective roles of Layton and Luke from the previous Professor Layton games and the anime film Professor Layton and the Eternal Diva.
Hiroki Narimiya (Gokusen's Noda, NANA's Nobu, Akihabara @ DEEP's Page) is playing Phoenix Wright (Ryuichi Naruhodo) in Takashi Miike's live-action film version, and he is reprising the role for Layton-kyōju Vs Gyakuten Saiban. Similarly, Mirei Kiritani (Arakawa under the bridge's Nino) will play as Maya Fey (Mayoi Ayasato) in both the film and Layton-kyōju Vs Gyakuten Saiban.
Sources: 1, 2, 3