Now, I have no idea, because when I battled the E4 in Diamond (my first independent adventure) I didn't modify my party whatsoever. All I did was train my Empoleon like there was no tomorrow. it worked (: Funny, I didn't give one single fuck about stats, types or anything back then. I just knew the basic water-fire-grass thing from the card game.
You played Diamond and you didn't know anything about the new types? Dayum, that's ballsy. I find that my party choices are based a LOT on what enemy type I'm facing. Very few types can be trained in all areas. Dragon is a notable example, and perhaps Normal type without a secondary type.
I have my GB color sitting on the floor with Blue loaded up. I've been trying to find batteries to use, but they all keep dying after ten minutes or so, even the lithium ones I found! I'm going to have to buy some. My DS has Black loaded up, but I haven't finished it yet. I own Blue, Yellow, Gold, Silver, Pearl and Black. I never had a GBA so I missed those when they came out. I did buy a copy of Ruby, but I haven't played past the second gym or so.
I've beaten Blue, Yellow, Silver, Gold, and Pearl, and I've completed the Dex for Blue, Gold and Silver. I'm really considering buying a HeartGold or SoulSilver copy soon, but I've already got two games in process and not enough time to play