101Leafy researched the games.
Bull Hammer

Hammer made from Bullfango, a beast whose merciless charge is feared by hunters.
| Class | Hammer |
|---|---|
| Rarity | 2 |
| Attack | 520 |
| Slots | 0 |
| Price | 1,400z |
Upgrades
| Upgraded from | Bone Club |
|---|---|
| Upgrades into | Bull Head Hammer |
Can also be made new at the smithy.
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.
Materials
Bullfango Pelt ×4, Bullfango Head ×1, Brute Bone ×5, Carpenterbug ×2
Plus Class Tcket ×1, Bullfango Pelt ×1