101Leafy researched the games.
Skullcrusher

Inlaid with numerous fangs, this Hammer could crush a wyvern's skull to dust.
| Class | Hammer |
|---|---|
| Rarity | 2 |
| Attack | 520 |
| Slots | 0 |
| Price | 1,400z |
Upgrades
| Upgraded from | Cyclo-Hammer |
|---|---|
| Upgrades into | Skullcrusher+ |
Upgrade tree from モンスターハンターポータブル 2nd G 公式ガイドブック (Enterbrain, 2008), page 724.