They are all weak to fire so it should work.
With the hammer you can't cut any tails or something like that.
For Royal Ludroth you want to keep your sharpness up so your hammer doesn't bounce of the spounge.
Gobul you will have to work on its head and watch and see if its body gets bigger and try not to hit its body then.
Gigganox it works well but since you have to be close to it you have to watch for its poison attacks and not hit it constantly or you will be poisoned. It can also have many ways to stall you when poisoned. Jump on the ceiling and do its roar.
For Laggi you have to try to try to set up your hammer attacks earlier since it moves quickly. under belly and back are your targets.
Rathlos and Rathian have good resistance to fire so your hammer isn't going to do much. Dragon and thunder are its weakness. Switch axes work well for both. Especially at cutting their tails.
When we were hunting the Great Baggi the other night, I ran into the Gigginox, but it was more like an ambush. I was using the hunter's armor and one single attack moved my health from maximum to nearly depleted.
I would like to hunt the Royal Ludroth online tonight and maybe the Quropeco again too to get a flint stone. I would also like to hunt a Rathian as well, but with two more people. Laslty, I want to complete my Barroth armor set before I try to beat the monsters on offline mode. I need to be strong enough to beat Gobul on my own.
Also, long swords are not available to me. I would not mind getting one though. Possibly flame based for mobilities sake because the hammer I am using is good, but it slows me down against faster enemies. This is why I was having trouble with Barroth last night.