I knew it was somwhere...
In Hero's trial they specifically state ships were using Ions ... um.... page 180-184 with the battle of Ord mantell
THey were even using B-wings. So i dont think there is any Crippling weakness exposed on Vong ships by using Ions on them
Also, the Dovin Basils (which is their biggest assest) are the engines and the shilds of the crafts, those would be underneath the Yorrik COral. And would be safe from Ion fire.
There might be a weakness, with using Tractor beams, in Onsalught, an Interdictor Crusier was VERY effective in disabling a Vong ship. Too bad there are not many Interdictors around.
maybe you coudl devlope some sort of EMP missle that is sort of liek a HESH (High Explosive Squash Head) anti-tank round. THe "missle" would peirce the YOrrick coral, and then set off a EMP Burst inside the Vong ship.. and if the missle was fired close enuf to the Dovin basils, the ship would end up being toast
All SW ships use hardend systems to prevent instentanious shut down due to Ion fire. It would make sense that Vong ships would be simularly hardended against the same.