Can I rate?
Porygon2: Same set I use.
Slowking: You could start with him to pass safeguard. If you want to drop him, I'd suggest Lapras or Starmie.
Houndoom: He doesn't have the defense to roar effectively. If you have it as a pseudo-hazer, I'd drop it for Dragonite with haze, fire blast, wing attack & T-wave or safeguard.
Machamp: If you dropped Doom for Draggy, try a Charizard here. It will fill the same roll with earthquake, rock slide, swords dance, and submission. Machamp works fine here though.
You have a 3x weakness to fighting. Also, Doom isn't much of a threat as a pseudo-hazer, seriously consider getting a good one.
How to ruin a Snorlax: