Gamespot did an interview with the peeps behind the Tekken game for PSP, heres an excerpt from that interview:
GameSpot: Why did you choose to bring Tekken Dark Resurrection to the PSP instead of a new Tekken?
Kazushige Watanabe: Bringing the latest version of the arcade to home consoles has always been the way we handle the series.
Haruki Suzaki: The nature of the PSP hardware allowed us to transfer Tekken the way it was meant to be in a way not possible on any other handheld consoles. For this reason, the decision to bring Tekken Dark Resurrection to the PSP instead of creating a new Tekken posed a challenge in testing the possibilities of the PSP hardware.
GS: What can you tell us about the dev team for the project? Which Tekken games have they worked on previously? How long has the game been in development?
KW: Most of the staff on our team has been with the Tekken Dark Resurrection PSP project from the start. There are veterans to the Tekken series as well as those working on Tekken for the very first time. Although, I must admit the number of staff with little prior experience to the series outnumbers the veterans. I can assure you that these are all developers who have worked on various titles before coming together on the current project. In a sense, we have a team full of experienced developers.