Tropes associated with two or more versions:
Tropes used in the OVA
- Designated Villain: Akiko is not so much a villain as she is a Mama Bear insistent on getting her beloved son Ryunosuke back. Plus, the description at the top mentions that Nuku Nuku is a stolen prototype owned by her company, after all. These provide reasonable motivation to pit her against the title character. Her antagonism is generally just played up for comedy.
Tropes used in Nuku-Nuku Dash: