Not to take anything away from what has already been said. Many good points on outmaneuvering and out controlling.
The ‘Super Mario’ deck you speak of is very powerful in some ways. Because it is so hard for many decks to stop, it usually wins against them. Super Mario definitely has its weaknesses. I’ll simply list some cards that are extremely effective against him, and you can get some ideas for your decks.
Cards that boot, send home booted, or move him.
Xiong “Wendy” Cheng, Soulblast, Pistol Whip, Run Em’ Down, Swinford Finds trouble, Ridden Down, Diable en Boite, Puppet, Paralysis Mark, Phantasm, Leonardo “Leon” Cavallo, Oddities of Nature (if you get unbooted abiniation to the town square first.)
Cards that drop Influence, bullets, or make mario a draw.
Rumors, Bloodcurse, Sun in your eyes. Faster on the draw, Incubation (after he’s been sent home booted), Tail between your legs,
Cards that affect hand rank.
Hex Slingin, Cheatin Varmint, It’s who you know, Ace in the hole (inderectly)
Cards that cause a casualty (seperate from 'take your lumps phase), or ace.
Legendary Holster, Shotgun (tricky, but there are value reducers), Takin you with me, Hot lead flyin, Point blank, Judge Harry Somerset (combine with send home booted cards, and you should succeed at the job)
Also important is that the opponent will only have so many actions to play a turn, so starting 2 or 3 separate shoot outs with him can leave him weaker.