Electabuzz: There are two trainers who have an electabuzz in B2. One is Ace Trainer Shaye who can be found in Chargestone Cave and the other is hoopster Derrick who can be found in Village Bridge
Skitty/Rufflet: Im sorry to tell you, but skittyand rufflet cannot be found anywhere in B2, but if you have no one to trade you could probably ask someone in chat to give you one to complete you pokedex.
Dusion: There are two trainers who have a dusion in B2. One is Psychic Bryce in Nimbasa City and another is Psychic Bryce in Celestial Tower
Pinsir: There are three trainers who have a pinsir in B2. One is backpacker Reece who is on route 14, another is Veteran Murphy in Lostlorn Forest, and the third is Black Belt Martell who is in Victory Road.