For your own sake play HG/SS.. D/P sucked ballz. Platinum was tolerable but never got me back into the series. HG/SS did because they were amazing. Didn't care much about B/W2.
Ah the good old days where you played for fun.
Stats are divided by physical and special, both split in attack and defense. This makes up how much damage your pokemon gives and takes. Depending on the generations, pre gen 3, physical and special were divided by type. Say, fire type moves were special, rock types were physical. In Gen4 they changed that, and it's now more realistic what move it is. Fire punch is physical, flamethrower special. So if you have no points in special attack, but the pokemon is a special attack user, it's gonna suck in competitive play. Each pokemon has a set of base stats, that decides what its strong and weak points are. Pikachu, for instance, has high speed and special attack stats, while a pokemon like Machop has high attack stat. Cloyster has high defenses(both special and physical), Chansey has high hp.... that kinda stuff.
Of ccourse none of this matters in the game, since you'll beat it easily. But if you want to try on the Battle Frontier, or online gaming, this stuff is essential.
Yeah I played professionally for a couple years with Emerald and DPPt.