DS
>Advance Wars Dual Strike (fun although broken strategy game) and Days or Ruin (more balanced and better map creator)
>Age of Empire DS (another nice turn-based strategy game)
>Ace Attorney trilogy
>Professor Layton games
>Nanashi no Game (horror game with a fan-translation available)
>Kumatachi (Vanillaware game about raising a bear girl in a small village, jap-only though)
PSP
>Gitaroo Man Lives (rhythm game with a super hero fighting against aliens/demons)
>Growlanser IV (big JRPG game from Atlus)
>Legend of Heroes Trails of the Sky (best Falcom JRPG titles)
>Disagea 1 & 2 (tactical RPG games)
>Boku no Natsuyasumi 1&2 (japanese summer vacation simulator, in the mountains on 1 or in an island on 2. Japanese only)