[BlackNhite]

Originally Posted by cheese4u

I doubt it, the rumble ball is Chopper's invention. For someone else to obtain it, they'd more than likely have to steal it, or the formula to make it from Chopper.

But if you're asking if someone else will acquire different forms with their zoan ability like Chopper then that's entirely possible. Afterall, we've already seen it happen with Rob Lucci.

Spoiler:

As for what Chopper is doing now. I would imagine that Kuma sent him to an island of doctors, but that would be way to obvious. Alternatively, I'm thinking Kuma may have sent all the strawhats to a place where they can work out their weaknesses. For Chopper his three biggest weaknesses is:

1. The three minute limit on the first rumble ball.

2. The mix up with the second rumble ball.

3. And his inability to control monster point.

Wherever Kuma sent him, I'm pretty sure it was to work out one or all of the three.

Spoiler for "Separation" Tales:

I was thinking that form current events regarding Chopper he ends up involved with a group or simply person(s) who themselves are Zoan users and, by some chance, notice Chopper using his Rumble abilities.
It could go any direction from there, I'd imagine any other average Zoan would find the ability to achieve four additional forms(perhaps more or less depending on the person) would be quite lucrative.

Damn, now I have the scenario in mind; perhaps Chopper will come across a band of pirates or maybe just a single marooned man who he nurses back to health(or even the reverse seeing as Chopper was in his "Monster Point" at the time). Somewhere in this period, Chopper is forced to use his Rumble Ball to protect/aid his patient(s)/savior(s). A Zoan user among the group is intrigued by the display, maybe he decides to take Chopper captive to make him more of those "special balls".

Not my most thought out scenario, but plausible and I still believe Oda is setting us up for some incident involving Chopper's Rumble.