All Purpose Cultural Cat Girl Nuku Nuku/YMMV

Tropes associated with two or more versions:

 * Cliche Storm: TV was a Widget Series featuring every well-known trope and cliche of the time, but utterly dedicated to playing around with each and every single one and not taking itself very seriously. Dash on the other hand, played its cliches to the letter and was tossed into Fanon Discontinuity for it.
 * First Installment Wins: The original OVA series is generally held in high regard as opposed to the overly bizarre TV series and the melodramatic Dash OVA. Though the other two still have their fans as well.
 * Puppy Love: (OVA) Ryuunosuke and Yoshimi. Even Akiko seems to think that Yoshimi and Ryuunosuke will eventually get married. In TV, Yoshimi is nonexistant, and this trope is the stated goal of Clingy Jealous Girl Next Door Noriko.

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 Ryuunosuke 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:

 * Fanon Discontinuity: Dash is generally disliked for making too many changes to the formula, among which are Ryuusuke being aged up from cute little boy to Ordinary High School Student and Nuku-Nuku becoming his hopeless crush instead of protector.
 * They Just Didn't Care: While preparing for her Heroic Sacrifice in the final episode (NOT a spoiler, trust me), Nuku-Nuku montages about all the good times she shared with Ryunosuke over the course of the series... including the scenes of them at the aquarium, which only ever took place in Ryunosuke's imagination. And that's just one example...