Hm. I've considered trying to fully complete the PokéDex in a game but I've never really given it a shot. I usually only catch the Pokémon that I use, something to learn HM moves, and then the legendaries just for a challenge. I was thinking I might try it with Soul Silver but doing it in a 4th generation game would be the hardest one to do it in. Plus I don't want any stupid Sinnoh pokémon taking up precious space in my boxes.
Though I wondered something: if there are 14 boxes and each box hold 30 pokémon, that means that you can only hold 420 pokémon in the PC at one time. But with the addition of the Sinnoh pokémon, there are now 493 pokémon. I know that most of them evolve so if you caught every pokémon and then evolved it through its entire evolution chain then there you'll have a lot less than 493 (it'd be interesting to see what the exact number is (the total number of evolution chains/pokémon families)). However, it's kinda of weird that it's impossible to have every single pokémon at one time.
I read a UU warstory once and I realized that the game is pretty drastically different. If I recall correctly, Spikes are a lot more prevalent in UU and the strategies are completely different too. I think I'll have to get a lot better at OU before I even try to make a UU team. I think that team building is my weakest skill right now. I'm getting better at prediction and finding counters for specific pokémon without having to tab over to smogon to check the Counters section of their new pokémon and run a few damage calculations. But I really struggle with putting pokémon that work well together in a team. Though the second team that I made was doing pretty well on the Smogon server last night.