I don't really like the idea of Bentley Bear in Smash that much compared to other potential Atari reps, mostly because I feel he has too much of a personality/theme to him and it wouldn't make sense for him to pull out space or high fantasy-themed props, let alone such props with a retro aesthetic. It's kinda like making the wolf from Egg the Game & Watch rep instead of a generic silhouette, sure: the wolf has way more personality and is much more striking to the eye, but he also has a specific theme that doesn't blend well with being lifted up by firemen or transforming into an octopus - in a similar way, I feel Bentley's Disney-esque kiddie fantasy aesthetic wouldn't work well with showcasing all of Atari's lineup in the way a cube with an arrow or a triangle that shoots lasers would.
