it's kinda tough...
Samurott is a water type with equally decent attacking stats, but no bulk nor speed to back them up.
Emboar is all right, but feels like he's just blaziken with a thicker body thanks to the type combo and distribution of his stats. I have a soft spot for him.
Serperior is actually pretty bad without it's dream world ability, which you can't access without a website that went defunct even before Nintendo pulled the plug on Nintendo WFC. that being said, nowdays in modern pokemon games where you have access to Contrary, Serperior is used pretty widely because of how dumb the Leaf Storm nonsense is.
Gen 5 I think was the first generation where I actually boxed my starter after getting Samurott for the Pokedex. My plan was to use Jellicent anyway, and Unova has plenty of wonderful pokemon to chose from.
Actually, one of the joys I've had with playing BW2 is seeing the way they've distributed encounters. This seems to be the first game where they adopted the mentality of making various areas of the game very densely occupied by wild pokemon, which struck me when I played X/Y for the first time as a good move; in that game's blatant Viridian Forest paralell, they specifically packed in just about every early bug-type line that you could ever want along with some other goodies new and old. Seeing early game Koffing, Grimer, Riolu, Mareep, Magby, and Elekid sprinkled in with your BW early game staples like Pidove, Lilipup, Patrat, and trubbish made me genuinely smile. (I'm the sort that in Sun/Moon ended up trying to SOS chain me the early game salamence)
So...my experience with the series is Blue/Red, and then dabbling in X/Y before dropping it. Sounds like B&W2 are what the majority are playing here, so I'll look-out for a cheap copy near me and see if I can scoop it up.
I'd take Pokepal's advice; play BW1. the big thing is that BW2 is so heavily remixed it's almost like a different game. VERY different narrative, completely different early game, refers to plot elements of BW1, etc. You even play as a different trainer and have a different rival.
also, the thing about BW1 is that they very tightly keep the Unova Ecosystem shut in. you will not see a Pikachu or any recognizable pokemon until after you have bested the endgame of Pokemon Black and Pokemon White, whereas BW2 is less concerned about that.