Custom Robo: So far all they've done is release the N64 games on NSO… but only in Japan. NoA does sometimes put untranslated Japan-only games on international NSO, but they only do it with games where the language barrier isn't an issue with understanding how to play and/or the story isn't very important (or non-existent). Like we did get things like Kirby Star Stacker and Panel De Pon (I imagine they have to discuss a new licensing agreement with The Tetris Company to re-release the international "Tetris Attack" version that replaced all assets with ones from Yoshi's Island), but are likely never gonna be stuff like Shin Megami Tensei or Fire Emblem 4 over here.

Chibi Robo: Best hope it's got is if Gamecube is added to NSO on Nintendo's Switch successor they could add it there, but I feel when it comes to new entries the chances are very slim.

Murasame Castle: Surprisingly it is on NSO in all regions, but it is odd that despite its popularity in Japan Nintendo's never bothered giving it a proper new entry. Suda51 said he'd love to remake it, and I'd be interested in seeing him work with Nintendo on a project.

Tomato Adventure: a localization or new entry is likely never gonna happen, and I feel a remake is unlikely. Better to just play a fan translation.

i want a new custom robo so bad bruh