Question

What determines if Dudunsparce is a three segment or two segment?

Answer 1

The form of Dudunsparce it evolves into depends on its encryption constant. Since this value cannot be influenced or seen by the player, what a given Dunsparce will evolve into is essentially random — with a 1/100 chance of evolving into Three-Segment Form Dudunsparce.

Source

Comments

I think that's a shiny hunt you need to do ty

---

I imagine this is also true of Maushold?

---

Yes, it's also true for Maushold.
Some extra context is available here: https://twitter.com/Sibuna_Switch/status/1596345370367647744