To be honest with you. You’d be better off heading up to the north island to target marlin. big kingfish and mako Sharks would be the ones to target in the north as well.
In the south we’re not as lucky as the north islanders. Although we do get kingfish over the summer months, they are not as common as they are up north. Another option could be bluefin tuna over the westcoast. but I’m not sure when is the ideal time of the year for these.
If it was me.. I’d organise a weekend trip to the top of north island with a well known charter operator. for the fish you want to target you’d be better off heading north.