I really enjoy pokemon games and it's my favourit game series. I try to catch all pokemon to complete my dex and I try to level up the ones I like. In pokemon black, I have more than 25 pokemon all around 40-45 level and I don't think that you can have more than that amount of pokemon at the same level before reaching the elite 4. As I said, I alter between pokemons because if you are going to stick to the same 6 pokemons for the rest of the game and leave the other 152 something untouchable where is the fun in that? So, I reached the elite 4 and I know that I won't be able to beat them because my pokemon levels are around 40-45 cloaking around 100 hours of play time. Thats how I enjoy pokemon, catch them, raise them, then switch to the next pokemons to raise up their levels. I have a friend who played pokemon white who only had 2 strong pokemon pegnite level 52 and stoutland level 60 and beat the elite 4 useing those 2 pokemons and his play time is 55 hours. Without gussing, he spent his time raising those 2 pokemon and ignoring the others. You see the difference here? My play time is 100 hours with around 30 pokemons (or more) with levels 40-45 and I cant beat the elite 4. I don't know where is the fun if you are going to focus on 2 pokemons and carry through the elite 4 and beat them.
When pokemon leaf grean/fire red came out, I had charizard in my party and I used to choose him only ignoring all the other pokemons. I remember I had him at level 60 when I rechaed the elite 4. I realized it's boring to rely on 2-3 strong pokemons and ignore the others. I change this boring strategy when other pokemon games came out, but it seems that the fun way doesn't work.