Here's what I'd do: clean slate.
It's obvious that at this point, the game cannot really be balanced anymore. To overthrow the massive forces we have now both due to moves and Pokemon being as close to broken as they can get, all you can do otherwise is add even stronger Pokemon, and that just gets you in the endless loop. Plus, if you introduce a hundred new Pokemon every time, things get even more on "team building chance" than they are now: the problem was there in ADV, and it is certainly my hugest problem with DP.
Maybe import a few "innocent" Pokemon from previous generations, but I'd say most of them have seen enough action as it is. If you start from clean, you can work on a balance from the start, as opposed to repeatedly add things to nerf one Pokemon and boost another.
For moves, I would take out/nerf:
- Draco Meteor (100 BP is plenty methinks)
- Stealth Rock (halve its damage, or cap damage at 25%)
- Spikes (back to 1 or maybe use 2 layers)
- Toxic Spikes (fuck off)
- Close Combat (even with 90 BP this is the best Fighting move, lol)
- Outrage (~_~)
- Baton Pass (sorry but no thanks)
- Double Team (so the debates go away)
I might be too obsessed with balance but I think at this point, with ~500 Pokemon available, "more is less". We've seen the Blissey line for long enough now and I daresay the same goes for Garchomp.
I really like this idea. Unfortunately, Nintendo won't do that. Each Pokemon and attack design is worth $$ to them, literally. It took programmers, pixel-artists, designers and sound-effect artists to create the finished product. They invested too much into each pokemon to start trimming down the game.
I do think the game has gotten too big. In all honesty, I'd like to see a mod-server take this approach. Contrast to the AA approach... instead of adding new features into the metagame to rebalance, we could simply do slight tweeks to the metagame and focus on a core set of ~60 pokemon to truly balance the game.
Not saying AA's approach is wrong, his server is quite interesting :-) (auto-rapid spin ability, stealth rocks modification, team-Eevee abilities... ditto arguably being OU material :-p ) But it is not the same feel and is a big jump from the current metagame.
Lets be honest here: 500 pokemon is enough for diversity. The problem now is that a few select pokemon aren't making the game diverse enough. Here is what I'd do:
1. I'd systematically balance theme teams. Sunny Day requires a lot of boosts, Rain Dance is close to usable but needs a bit of improvement. Hail and Sandstorm are fine as they are. From there, I'd add more theme type strategies... beat-up has potential for an all physical team. It needs to be improved. Tailwind needs to become a full weather effect (knocking out hail, sandstorm, etc. etc.) last 5 turns and have an item that boosts it to 8.
Some initial ideas are to turn "leaf guard" into a "hydration" like effect in Sunny Day (as opposed to safeguard-like), boost more Grass Attacks than just SolarBeam, and turn Sunny-day based healing into 40% minimum, 50% w/o weather, and 66% with weather. Honestly, Sunny Day teams get raped by all 3 other weathers because Moonlight / etc. etc. drop down to friggen 25%... Up the PP of those healing attacks to 10 pp.
Both Drizzle and Drought need to come to OU play. I'm thinking politoed.
A few dual-weather teams should be usable to take advantage of Castform and Roserade's Weather Ball, as well as cool combos like Blizzard / Thunder. Obviously, hard to pull off, but not impossible.
2. "Early Game Over" and "NPC like feel" need to get out of the game. Baton-pass teams win after maybe... 10 turns if they last that long. The next 20 turns are them beefing up their attack enough so that they can actually sweep. Each turn should be a battle. "Short" Baton Pass teams seem to be very balanced, with their share of bad effects, but deep 10 turn Baton Pass teams are no fun to play against once it is clear that you've lost. To that effect, maybe each +2 boost lasts only 5 turns, while +1 boosts last forever. Calm Mind, Bulk Up, Cosmic Power and Dragon Dance count as +2 boosts. Meditate, Defense Curl, etc. etc. are +1 boosts.
3. Merge items together. We don't need 2 ways to boost your attack by 20%, we don't need a different rock for each weather. I think the plates might have to go up to a 30% boost, and Muscle Band and Wise Glasses up to 20% boost in power. Leftovers, Life Orb, Choice Band, Choice Specs are too common, make the other guys a bit stronger.
4. Hyper-beam attacks should actually be worth using. Knock all of them up to 200+ BP at least, maybe more depending on testing. They have a cool mechanic, but it isn't worth using them at the moment.