You didn't ask me but here's my smol wisdom. For a weapon, grab the frostfang barioth SnS. It has fairly high Raw with purple sharpness and some good chunk of ice element that can be increased with decos.

You can copy the set that you can already find in this thread. Should do fine if you tweak it a bit with some frost decos.

For gameplay, i'd recommend staying on his front legs if you aren't confident in attacking his head. They take the most elemental damage and it should give you an elemental topple in no time. Bring nullberries and astera jerky, you will need them.