IIRC, Lightning based weapons are the most effective against Tiggy. much more-so than fire. regardless of rank, my main Anti-Tiggy weapon is the TDS and the rest of the Devil Slicer family [on my way to making the Wailing Cleaver now. gonna take a while to get the parts though....still in HR6....]
been having a weekly MH marathon with 3 of my friends. every weekend we get together and blow through a few quests together. my main Hunting Buddy and i've been helping the most recent two to climb through the ranks. we descended the heights of the Hunter Ranks to help them with an Urgent Quest against Ashen Lao

...once we hit HR6 i'm probably gonna hault all our Co-Op work and tell them to work through the Elder Ranks until they're finished....seeing as the Guild Quests aren't giving them enough materials to properly upgrade considering we only do any quest once...once everyone's got decent gear....we take the G-rank quests by storm...