Its a pretty big assumption to say that Coco isn't as strong as Tommyrod, given the fact he went toe-to-toe with Grin. Mold spear isn't just a simple projectile, it's a near light speed attack which can pierce through an opponent and Sunny hasn't shown anything like the reactions to be able to deal with it.
Coco wouldn't use gaseous poisons, he'd simply coat himself in the deadly poison he has, negating a lot Sunny's hair abilities. Sunny's main chance of winning would be to retreat and throw projectiles via super hair shot. If he used any feelers, Coco could simply send poison through the hairs.
Sunny having time to prep is almost irrelevant, Coco's intellect and battlefield awareness dwarfs any of the other kings.