[806mtson]

The Neo Batta Vistamp is actually mostly a newer mold. It is a slight retool of the Batta Symbol, but the background is Zero-One's Face. The Neo Batta Symbol is actually a remold of the original instead of being a redeco. The Left "Wing' of the symbol is actually in a different location. And there is part of the Left "Wing" right behind the head.
According to the Wiki, the announcement for the Neo Batta Vistamp is "Hiyaku o chikatta! Kibō to natta! Neo Batta! Revice ja 〜 naito!"
Though it appears that the Zero-One=Giraffe Rumor was just a rumor and not true at all. At least this makes more sense.
I think the reason why they chose this Zero One-based Form is that otherwise, it would be kind of confusing and would be kind of weird for Saber to see Revice looking like him.
Though, this gives signs that the same animal could be the basis for multiple Vistamps.
Also, I bet the reason why some of the animals don't make sense is because of 1 reason that is besides any attempt by me or others to make connections between the Vistamps and their Rider basis: The Limited Amount of Real Animal Motifs of the established Riders.

I mean, Kuuga was based upon a Stag Beetle, Agito was based upon a European Dragon combined with a Stag Beetle, Ryuki was based upon a Chinese Dragon combined with a Medieval Knight, Faiz, specifically Takumi, was the Wolf Orphonoch, and had motifs of the Greek Letter Phi and a Shark, while as Delta, he combined an Asian Ant Mantis with the Greek Letter Delta, Blade combined a Hercules Beetle and the Spades Suit, Hibiki combined an Oni, a Drum, and Kumadori, Kabuto was based upon a Japanese Rhinoceros Beetle, Den-O was based upon a combination of a Bullet Train, the Railroad, a Clock, and Fairy Tales, Kiva combined a Bat, a Vampire, a King, and, a bit weirder, a Jack-O-Lantern, and Decade combined a Barcode, the Number 10, a Decade, and an Italian Striped Bug. That's just from Heisei Phase 1. Not that much variety in motifs. Most of them are based upon Bugs, and having another Series with every Rider having Bug Motifs like Kabuto wouldn't be that interesting. So, out of necessity, they had to create the Vistamps trying to connect an animal to each Rider that isn't as simple as basing them all from Bugs. Seriously, just from the Riders I named, two were based upon Stag Beetles, five had motifs based upon characters from Mythology/Fiction, four were based upon Beetles, and then there were those added Motifs like Barcodes, Greek Letters, Trains, etc. Seriously, how do you link a Barcode to an Animal besides Tigers or Zebras? How do you link Trains and Fairy Tales to an Animal? How do you link the Letter W or the Cyclone and Joker Memories to an Animal? How do you link an Astronaut/Rocket to an Animal? How do you link most of the Kamen Riders from the Heisei Era, the Showa Era, and/or the Reiwa Era to an Animal when most Kamen Riders are based upon Grasshoppers or other Bugs? You'd have to get creative with the Motifs you link to each Rider.

Also, the fact that Revi's Color scheme doesn't change was likely because they wanted to keep using the Revi Rex Genome Undersuit. Otherwise, creating 10 Unique Undersuits for the 10 Main Revi Forms (Rex-Brachio) would be overly expensive. Seriously, any cosplayer (which I am not) would know that making 10 Unique Costumes that would likely only get used so often would get expensive. Also, just using Revi's Undersuit, but adding other colors on the other forms would get pretty ugly, considering that the undersuit is Bright Pink (not Magenta) and Light Blue. Dark Green, Bright Pink, and Light Blue could clash, but especially Orange, Dark Blue, Light Blue and Bright Pink. Some of those Colors Schemes would just not work. Also, using the Vice Kong Genome Suit as the Basis for the Brachio Genome Suit is also clever as otherwise, how often would they use Kong Genome?