I thought I remembered reading somewhere that Monstrous Cavalry use the highest Toughness on the model, but when I went to look that up, I only found that you use the highest Wounds of the model, and that for everything else you use the rider's characteristics. So, does this mean that shooting and close combat attacks against Ripperdactyls will use the Skinks' Weapon Skill and Toughness of 2?
They follow regular rules for calvery as well. I think it might be in that section. I think you are confusing monsterous cav with ridden monster rules.
It is found in the BRB FAQ: "Page 83 – Monstrous Cavalry. In the second paragraph, replace “All the cavalry rules…with one exception – monstrous cavalry always use the highest Wounds characteristic…” with “All the cavalry rules…with two exceptions – monstrous cavalry always use the highest Toughness and Wounds characteristics…” "
Yup, and this means that those woodies can have a nice toughness 4 from mounting their lords and heroes on stags. just like their dark elf counterparts with the dark pegasus.