This decks is what I'm using. Its cheap, so you can spam cards if necessary when defending. Enforcer Jimmy and Heidi is great for that.
I built this deck mainly to counter all the people that run mind control-cards, because it's annoying to play against and a very common strategy. Mecha-Timmy - Smite him with Lightning bolt. Cyborg-Kenny, mind-Control him instantly.
Another strategy many people use is to send out headhunter-Doogie, just mind-control him instantly or put out dog poo that one-hits him close to your leader. That's not a problem.
For those opponents who push hard, just put out sheriff-cartman at front and poison the pushing mob, then you put mephisto behind, that combo gives huge AoE damage - especially when cartman is charged.. Once you have enough energy after that - spawn Stan of many moons in the back to protect mephisto and cartman when they push. Make sure to have mindcontrol ready if the try to steal Stan and use his ability against you when he approaches the middle of the field.
The biggest counter to my deck is Big Gay Al combined with fireball or Officer Barbrady combined with fireball. I dont have an answer for that. Otherwise i win almost every game vs players that are no more than one level higher than me.
I'm currently level 16 and play in legendary League, all of my cards are level 5 atm. =)