The staff page (booklet 28) credits two TOSE audio people under "Game Boy Version" (ゲームボーイ・ヴァージョン):
Akihito Suita (吹田 明仁) and
Yoko Matsutani (松谷 陽子). This is the only appearance I'm aware of of Matsutani's name in kanji; TOSE game credits tend to be in English so it's pretty hard to confirm the names of most of their guys in Japanese.
I have no idea what "Game Boy Version" means here, though. My initial thought was they did the GB arrangement or sound programming, but nothing like that appears in the credits:
http://www.geocities.jp/bgrtype/gsl/...qmonsters.html. There are two people credited with "music compose assist": "ASD･BAT" and Kazuki Kikutani. Of course, Sugiyama is the only person credited for composition in the booklet. 8)