* MarthDebutedInSmashBros: Some robo models, including the [[SeriesMascot Ray Mk II]], appeared as collectible trophies in ''VideoGame/SuperSmashBrosMelee''. This was the first appearance of these characters on western shores, which sparked interest in the franchise, leading to the release of ''Battle Revolution'' in the US, and the release of ''Arena'' in all regions.
* NoExportForYou: Neither of the N64 originals (''Custom Robo'', ''Custom Robo V2'') were ported to Western shores.
** Nor was ''Custom Robo GX'' for the Game Boy Advance.
*** ''Custom Robo: Battle Revolution'' [[SequelFirst made it to the US]] as just ''Custom Robo''. Not the EU, though, making ''Custom Robo Arena'' the '''only''' game available to the in all regions.
*** In a somewhat unusual example, the various versions of the games have region-locked Wifi, creating separate networks for each of the JP, US and EU versions. This basically means that a European player cannot battle Japanese or American players, and vice versa.
* RecycledScript: ''Arena'''s plot and and overworld graphics are recycled from a canceled GBA Custom Robo game, hence their primitiveness.
* SequelFirst: The first game in the series to be released in the US was ''Battle Revolution'', which was for the [[UsefulNotes/NintendoGameCube GameCube]].
* WhatCouldHaveBeen: The Misty Mirage class of robos from ''GX'' have well rounded stats and a unique 'Mirage Dash', which rendered them completely invisible for a short period of time and enabled them to phase through walls, while retaining full regular movement instead of a quick burst of speed.[[note]]Unlike Strike Vanishers and Burning Beasts, however, they can't dodge gunfire during the Mirage Dash[[/note]] While completely redundant against the AI, this allows for mind games and sneak attacks against human opponents. Sadly though, they have not appeared in either of the subsequent titles, likely because they'd be difficult to implement in a 3D environment.