Yux

From left to right: Yux, Z-Yux, X-Yux
Mini Yux, Mini-Z-Yux, Mini-X-Yux

X Creatures that were created by X-Naut scientists and can create Mini-Yuxes to create barriers around him.

Paper Mario 2 Stats and Tattle Information

X-Yux's Stats: HP: 10, Attack: 3, Defense: 1
Mini-X-Yux's Stats: HP: 1, Attack: 0, Defense: 0
Tattle (X-Yux): That's an X-Yux. I hear this is read as "Cross"-Yux, not as "Ex"-Yux. Anyway, this is a new Yux designed to protect extra-important areas... They were designed to be unbeatable. They're not. It can produce two Mini-X-Yuxes at once. AND, it has an excellent success rate of immobilizing opponents. We gotta do something about that if we're gonna win.
Tattle (Mini-X-Yux): That's a Mini-X-Yux. It lives to protect the X-Yux. Up to 4 can guard the X-Yux. Max HP is 1, Attack is 0, and Defense is 0. You can't attack the main unit until you clear these annoying pests out. So use multiple-strike attacks to take them out all at once!
X-Yux's Tattle Number: 114
Mini-X-Yux's Tattle Number: 115
Tattle Log (X-Yux): A new Yux designed to protect important areas. Its attacks will sometimes immobilize you.
Tattle Log (Mini-X-Yux): A protector of the X-Yux. You can't attack the main unit until you clear these things out.

Yux's Stats: HP: 3, Attack: 2, Defense: 0
Mini-Yux's Stats: HP: 1, Attack: 0, Defense: 0
Tattle (Yux): That's a Yux. Says here it's a creature created in the X-Naut labs. According to this, attacks and items won't affect it if it has Mini-Yux around it. So if any Mini-Yux appear, take those out first. Duh!
Tattle (Mini-Yux): That's a Mini-Yux. A creature made to protect a Yux, it can split into two. These twerps are the reason you sometimes can't do any damage to the main Yux. They're a pain, but you HAVE to beat them before the Yux. Flurrie's pretty effective...
Yux's Tattle Number: 110
Mini-Yux's Tattle Number: 111
Tattle Log (Yux): These pathetically ugly creatures were created in X-Naut laboratories. With Mini-Yux around them, they're impervious to all attacks.
Tattle Log (Mini-Yux): Each one can divide into two. As long as you clear these out first, ordinary Yux are nothing to be feared.

Z-Yux's Stats: HP: 7, Attack: 4, Defense: 0
Mini-Z-Yux's Stats: HP: 2, Attack: 0, Defense: 0
Tattle (Z-Yux): That's a Z-Yux. It's a genetic improvement on the original Yux. Multiple Mini-Z-Yux will appear to protect the main unit, as you'd expect. Sometimes they also restore HP to the main unit, which really burns me up! It doesn't have much HP, but those barriers often protect it from attacks.
Tattle (Mini-Z-Yux): That's a Mini-Z-Yux. It lives to protect the Z-Yux. There can be as many as 4. If you don't clear these guys out, you'll never be able to attack the Z-Yux. Using a multiple-strike attack to take them out all at once is a totally good idea. I mean, I respect them for protecting their... whatever, but they get NO mercy!
Z-Yux's Tattle Number: 112
Mini-Z-Yux's Tattle Number: 113
Tattle Log (Z-Yux): A genetic improvement on the original Yux. Mini-Z-Yux often appear to restore HP or protect the main unit from damage.
Tattle Log (Mini-Z-Yux): A protector of the Z-Yux. There can be as many as 4. They must all be defeated to make the Z-Yux vulnerable.