I'm here with the newest card combo I found today and another way to stop Slowking. Let's Look at the cards, (Forretress info is from Bret Larwick's Neo2 spoiler, just reformatted)
 
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Beedrill                80 HP
Evolves From Kakuna
 
G ~ Triple Poison 10
Flip a coin. If heads, the defending pokemon is now poisoned. Your opponent now puts 3 damage counters on it instead of 1 after each player's turn (even if it was already Poisoned)
 
GGC ~ Pin Missile 20x
Flip 4 coins. This attack does 20 damage times the number of heads.
 
Weakness                    Resistance               Retreat Cost
    Fire                            Fighting                        None
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Forretress               80 HP
Evolves from Pineco
 
Pokemon Power: “Spikes”
During your opponent’s turn, whenever 1 of your opponent's benched Pokemon becomes his or her active Pokemon, Forretress does 10 damage to it. (Don’t apply Weakness and Resistance.) This power stops working if Forretress is Asleep, Confused, or Paralyzed.
SCC ~ Rapid Spin 30
If your opponent has any Benched Pokemon, he or she chooses 1 of them and switches it with their Active Pokemon; then, if you have any Benched Pokemon, you switch 1 of them with your Active Pokemon. (Do the damage before switching the Pokemon.)
 
Weakness                    Resistance                Retreat Cost
    Fire                             Grass                             3
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Now, Beedrill's Triple Poison, absolutely amazing. Now, If you can get heads, here's where Forretress comes in. They'll want to retreat. Forretress, however, puts a burden on them to retreat. Add a little gust with this to make all of your opponents damaged. Then comes Sabrina's Gengar to finish 'em all off at once.
 
Now for the other way to stop Slowking, it might be known, but........... Muk! Now most people would say, "Yeah, and look at Muk's weakness" Well, now comes..... Mr.Mime! Mr.Mime's weakness will prevent damage from Slowking. But, Slowking can confuse. Now to finish off Slowking's confusion comes....... Promo Venusaur!
(This info comes from Bret Larwick's Promo spoiler [reformatted])
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Venusaur                80 HP
Evolves from Ivysaur
 
Pokemon Power:"Solar Power"
Once during your turn (before your attack), you may use this power.  Your Active Pokemon and the Defending Pokemon are no longer Asleep, Confused, Paralyzed, or Poisoned.  This power can't be used if Venusaur is Asleep, Confused, or Paralyzed.
GGGG ~  Mega Drain  40 
 Remove a number of damage counters from Venusaur equal to half  the damage done to the Defending Pokemon (after applying Weakness and Resistance) (rounded up to the nearest 10).  If Venusaur has fewer damage counters than that, remove all of them.
 
Weakness                    Resistance                Retreat Cost
     Fire                             None                            2
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This card will make Mr. Mime unconfused (is that a word?). But you'll need some Hyper Devolution Sprays (Neo2) to keep Muk.
 
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Email me at Serebii_Masta@thepokemasters.com
 
Serebii Masta