It's been a very long time, and it always surprises me when I see a Pokemon from Gen 1 and I can name it instantly despite not thinking about Pokemon since maybe 2000 (I didn't get Gold/Silver because I didn't have a Gameboy Color, thinking on it, I have no clue what Nintendo was thinking there, they would have sold more copies if they made it for original GB as well). I was one of those kids who got every Pokemon, knew every name, traded for new ones until I got the full Pokedex. I was heavy into Pokemon from fall 1998 (when the cartoon first aired) to 2000. I played that game for at least a year and a half, on constant rotation.
Magnemite is awesome. It is an absolute beast. I beasted my way through Gym 2 with it, getting it all the way to level 17. It counts as a steel type, right?
I'm surprised by my lack of use of Uvola region Pokemon. I'm using stuff like my handy Psyduck, my Riolu, Magnemite, Lillipup, Magby, and Venipede. I picked Snivy but Snivy sucks.
Also on that note, SA > Andrex. I said I haven't played Pokemon in over a decade and wanted advice, and they were helpful instead of belittling!
BW(2) has changed the way EXP is calculated, which works in your favor if you're trying to level up a new Pokemon or if you like switching around your team a lot. If your Pokemon's level is lower than the opponent, it gets more EXP. If your Pokemon's level is higher than the opponent, it gets slightly less EXP. Don't be afraid to try out a bunch of new Pokemon, in other words.
Whether an attack is physical(based on the Attack stat) or special(based on the Special Attack stat) is no longer based on type. Instead, it depends on the move - physical moves have a [timg]http://i.imgur.com/kDBS7.png[/timg], while special moves have a [timg]http://i.imgur.com/iVYXe.png[/timg]. Moves with [timg]http://i.imgur.com/puZng.png[/timg] generally deal no damage, but have a special effect instead.
There are a bunch of new Balls now, and most of them are better than even the Ultra Ball if you use them correctly. The description of each one tells you when the best time to use them is. The biggest one to keep in mind is the Dusk Ball - it's most effective when it's night time or when you're in a cave. Several Legendary Pokemon are found in caves, so using Dusk Balls on them can cut down on hassle.
Money's rarely going to be concern once you're past a few gyms. Sell off those useless X Items if you need more.
You have unlimited inventory space and TM's are now infinite use. HM's are completely optional and used only for accessing hidden areas.
Dark and Steel types now exist.
Dark is:
Immune to Psychic
Resists Ghost and Dark
Weak to Bug and Fighting
Super Effective against Ghost and Psychic
Not Very Effective against Steel, Dark and Fighting
Steel is:
Immune to Poison
Resists Bug, Dark, Dragon, Flying, Ghost, Grass, Ice, Normal, Psychic, Rock and Steel
Weak to Fire, Fighting, Ground
Super Effective against Rock and Ice
Not Very Effective against Fire, Electric, Water, Steel
Pokemon can now hold items in battle which can various effects, eg: Oran Berry which restores 10HP once the holder's HP drops below 30%.
Pokemon now also have Abilities which are provide a constant, passive, bonus. eg: Levitate, which makes any Pokemon that has it completely immune to damage from Ground type moves.
