I don’t know how to get around smiley poison ability without poisoning my good phobius.
If it’s a poison phobie you need to fight use a mechanical card
Undead phobies could work too. Since they leech health, they could collect enough health to survive the disease.
Disease is permanent, so there is no way of surviving that expect of constant healing or finishing the game early.
The best way to deal with Smiley are mechanical units. Ranged phobies like Heavo, Motherload or In-Oculus would be the best, but you can also use melee mechanicals to simply block the path. If you can’t afford those, you can try to minimize your loses - losing a phobies worth of 5 keys in order to kill smiley isn’t a bad deal. Even if your units are diseased, you can still use them to capture panic points and injure enemies. If we put it that way, a 5-key trade might be actually good for you.
Keep in mind that Smiley is really slow. Even if he diseases your phobies, they will survive few turns. Sometimes it’s a good idea to make a pressure, because enemy has just played a 5-cost phobie that won’t do anything significant for a while.