I love the feature in the Dual-type page, it is very instructive, specially where you show the combinations with the least and the most weaknesses.
Besides that, every time a new generation is coming, we all wonder what dual-types not explored will finally show up.
So my suggestion is to make a section on each Type page, maybe below the "Notable Type Trainers", with "Dual-type combinations with this type still missing" and the list.
For example, "Dual-type combinations with Fire still missing" and below the list with "Water/Fire; Grass/Fire; Electric/Fire; Ice/Fire; Poison/Fire and so on".
It would be really nice.