I've been experimenting more with Dtilt near the ledge, and it actually seems like a really useful gimp tool. It hits them backwards (like Samus/Peach Dsmash), so they are forced to up-B (or otherwise turn around) if they want to grab the ledge. Getup-Dtilt and ledgehop-Dair-Dtilt both seem to work if the opponent doesn't expect it. Definitely a gimmick though
(RE: Pokemon Stadium Transformations)
Doc's Bair and Ftilt will hit through the transformations, though not as well as other characters. Try crouching at the base of the tree and then full-hop Bair after an opponent on the other side whiffs an attack! Doc's Pills are also pretty good on transformations, try using the slopes to bounce the pill in interesting directions. Shooting the pill just over the tree (from left to right) will get the pill to bounce backwards at the base of the tree, and is a really good way to harass an opponent camping the bottom right side of the tree. Also, the slopes make horizontal wavedashes really easy, which can get you a lot of surprise approaches.
(RE: Full-hop pill/Nair stuff)
full-hop Pill, Nair, or Dair all leave you with a window to act right before you land. As SuperWorri0 said, you can Nair right before landing, but that's not too useful. Y'all probably know about the double-jump, lots of Docs will FH-pill-DJ-pill. Uair and waveland are also really good options that will often surprise your opponent. I like to FH-Dair-Uair and FH-Pill-Waveland (either forwards or backwards, as Desh mentioned. Be tricky!) Full-hop pills can be pretty useful on platform stages too, as they will hit opponents sitting on the platform (though if you land on a platform yourself, you won't be able to do any of these waveland shenanigans)
(RE: Nair off-stage)
Nair is really good for covering an area when you're not totally sure on the timing, but are confident your opponent will have to run into it. I find it most useful to edgeguard Fox/Falco's side-B. Or if you read a double-jump but aren't sure on the timing, put out a Nair above their head and hope they jump into it. On that note full-hop Nair above a Fox/Falco in shine or an opponent in shield is also really useful, as they usually will jump into it.
(RE: Smashboards Dying)
yeah... it's sad. I frequented this forum 3 years ago and there was always a good amount of activity. I should visit here more often, but frankly I'm busy doing other crap and also I'm not really sure I would get that much from here, honestly =X. The Great Facebook (and Reddit) Migration really killed things. A big part of it is that old-school style forums aren't really a great way to organize this sort of conversation. All the technical information would be better in a wiki, and the casual/multi-threaded conversation works much better on Reddit.
Also, like OTG, I've been playing a lot more Fox lately. 20XX is real. Doc isn't very good tbh, I think he'll be below Samus when the dust settles. With that said, keep Doc alive! He's loads of fun to play, and honestly I think he transitions well into most other characters.
(RE: up-B cancel)
I can only up-B cancel about 15% of the time, nowhere near consistent enough to go for in a match. Personally, I don't think it's that useful. I'm a big fan of up-B OoS and landing on the top platform of Yoshi's or FoD though.