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The move 'Protect' is a 100% counter to Slaking, whom I assume you have problems with.
Simply Protect on the turn they attack, attack while Truant activates, and repeat.
All of Norman's other pokemon are kinda easy due to their low defenses, the only major problem is Slaking.
Pretty much Aquillae's Strategy is an excellent one.
You should Train some more Pokemon, 2 is a bit low, it becomes really hard in certain gyms, when you have 1-2 pokemon, i suggest that you train some more. Although, most people do fine with little pokemon.
Vigoroth will be a problem, as will Spinda and Linoone. Fighting type moves to attacks are your best bet to KO a normal type Pokemon. Ghost Pokemon are very good against normal types since they absorb normal moves like Facade, although that means you can't use any ghost moves against that either. As Aquillae said, use the Protect strategy against Slaking.