Serperior is pathetic without Contrary. Send in a Grass type to protect against Leech Seed. Ferrothorn is going to resist everything Serperior throws at it, especially since it will unlikely have HP Fire due to it being hard to get ingame. You can then use that time where Serperior can't hit to get in Curse, or set up Entry Hazards if you bred for them. Gyro Ball can then KO Serperior when you are done with Curse/Entry Hazard.
Emboar is best taken down by Chandelure. Flash Fire protects you from its Fire attacks, and Ghost typing protects from its fighting type attacks. However, it will likely have Rock Slide or Head Smash. As such, give Chandelure a Choice Specs and hit hard with Psychic.
Samurott doesn't really require much thought to take down. I'd just use Jellicent, which is immune to Water type attacks thanks to Water Absorb, resists Ice, and resists Bug. You can then hit Samurott hard with Energy Ball.