Answer: NOGUARD
Explanation: As the No Guard ability makes all moves 100% accurate, Dynamicpunch's fatal flaw (its 50% accuracy) is nullified on Machamp that have the ability, giving them an accurate, 100-power move that always confuses. Nasty.
Answer: EXEGGCUTE
Explanation: Well, it's called ExeggCUTE, but it looks a lot more evil than cute. At least to me. o.o
Answer: PICHU
Explanation: In the first generation, Pichu obviously didn't exist. In the second breeding was new and being introduced. In the third, you'd need to get a Pikachu from the Safari Zone and then breed that. However, in the fourth generation Pichu can be found in the wild in the Trophy Garden.
Answer: BRONZOR
Explanation: Bronzor is a mirror Pokémon, it is (along with its evolution Bronzong) annoyingly common in quite a few caves, and on its back sprite there is a pattern resembling a simplified image of a tree or branch. This, of course, makes very little sense, considering Bronzor is a Steel/Psychic type and has nothing to do with plants.
Answer: DIALGA
Explanation: Dialga's signature move is Roar of Time. Roar is obviously another attack, and Roar of Time makes RoT, or 'rot'. Pleasant.
Answer: CHINGLING
Explanation: 'Chingling' is basically the sound of a bell chiming.
Answer: ARCEUS
Explanation: Arceus is a god Pokémon, and in the Pokémon world one could guess that that would be the kind of god worshipped in a church. Apparently not.
Answer: SHAYMIN
Explanation: Shaymin's Japanese name is 'Sheimi', which could be romanized as 'Shaymi', but where that n came from I have no idea.
Answer: EMPOLEON
Explanation: Penguins live mostly in Antarctica, the coldest continent on Earth and pretty darn icy. On the other hand the Steel type more suggests something man-made, which is kind of ironic since Antarctica is also the only continent not inhabited by humans.
Answer: BIDOOF
Explanation: Uh, the clue speaks for itself.
Answer: ELECTIVIRE
Explanation: To obtain an Electivire, you must 1) get your hands on an Electabuzz, 2) own FireRed and have it in your GBA slot, and 3) get an Electrizer from the wild Elekid that will then appear. I doubt there is any Pokémon more of a hassle to obtain than Electivire and Magmortar, save the event legendaries and Milotic. However, Electivire was one of the first D/P Pokémon to be brought before fans' eyes.
Answer: UPROAR
Explanation: Uproar prevents Pokémon from sleeping so it makes the best status condition for catching just about impossible to inflict on Azelf. Its Uproar is further made annoying by Nasty Plot, which sharply raises its Special Attack and thus powers up the normally weak move to formidable strength.
Answer: PONYTA
Explanation: Ponyta is the only Fire-type obtainable in Diamond and Pearl before the Elite Four aside from the Chimchar line, making it basically the only possible Fire Pokémon for those who picked Turtwig or Piplup.
Answer: HEARTHOMECITY
Explanation: Hearthome City is cited by many in-game characters to be a good, family-friendly place to live. Among the NPCs who praise it is a woman who says that she wants to live in Hearthome City but her boyfriend wants to live in Veilstone because of the Game Corner, which is a possibility she does not appear to be particularly attracted to, hence the clue, which was supposed to tip you off to remember that woman.
Answer: OVALSTONE
Explanation: The Oval Stone evolves Happiny into Chansey, which always used to be one of the most elusive Pokémon in the game. Now, however, Chansey are fairly common in the wild, so we don't have any particular need to evolve a Happiny.
Answer: POLIWAG
Explanation: In Pokémon Ranger, the description of Poliwag says that it does this (which can easily be confirmed if you confront some Poliwag in the game).
Answer: GYARADOS
Explanation: Waterfall is a physical move in Diamond and Pearl. Out of the Pokémon that can learn the HM, the highest Attack belongs to Rayquaza (150 base), then Dragonite (134 base), and then Gyarados (125 base). However, as Rayquaza and Dragonite do not get STAB for Waterfall and Gyarados does, Gyarados will nonetheless pull off the most powerful Waterfall of all Pokémon.
Answer: DEVONGOODS
Explanation: All the Pokémon games have early on included an errand where you must deliver a key item to another character. In R/B/Y, the errand was to take Oak's Parcel to Professor Oak; in G/S/C you had to give Mr. Pokémon the Togepi egg; in R/S/E you needed to deliver a Letter to Steven and the Devon Goods to Capt. Stern, and in D/P you have to take a Town Map to your rival. Thus, like you need to deliver the Town Map in D/P, you need to deliver the Devon Goods in R/S/E.
Answer: SUICUNE
Explanation: All of those nonsense sentences ('aged nerd thinly worn', 'threading drew nylon' and 'a lending nerdy throw') are anagrams of 'north wind legendary'. Once you've figured that out, the connection with Suicune is obvious.
Answer: GLISCOR
Explanation: Gliscor's D/P sprite looks at a glance like it's almost symmetrical (which is a very great sin of spriting), but in fact a pixel-by-pixel comparison will show that the two sides, though similar, are not quite the same.
Answer: HEATRAN
Explanation: Heatran is in Stark Mountain, but only after you have retrieved the Magma Stone with Buck at the very place where it later appears, so you are forced to go through the mountain twice to get Heatran.
Answer: MANAPHY
Explanation: It is with Manaphy as with the other legendaries coming at the end of the regional Pokédexes: it can only be obtained by going to events or by using a special code. However, unlike in the others' case, the Manaphy code is a mission code for Pokémon Ranger, not a Gameshark or Action Replay code, so it does not require cheating.
Answer: LUCARIO
Explanation: Before the release of Diamond and Pearl, people persistently believed that Lucario had to be a legendary Pokémon since it starred in a movie. Later the evidence against that just piled up: it had non-legendary stats, a pre-evolution, a gender, no Pokédex number of any significance and is owned by three trainers in-game. It is now clear that Lucario is a non-legendary.
Answer: ELECTRIZER
Explanation: You use the Electrizer item to evolve Electabuzz into Electivire (26 across)
Answer: DRIFBLIM
Explanation: Drifblim's English name was originally reported to be 'Driftblim', but obviously turned out not to be.
Answer: MAGMORTAR
Explanation: I mean, the Magmar family are Fire Pokémon, but nonetheless it's LeafGreen rather than FireRed you need to have in the GBA slot to find wild Magby with the Magmarizer that you can use to evolve your Magmar into Magmortar. (Yes, I know Magmar is the LeafGreen exclusive and Electabuzz the FireRed one; I'm musing at the fact it wasn't the other way around to begin with, plus that technically we'd be much better off getting Magby by inserting FireRed, since if we have FireRed, we obviously have more need for a Magmar than an Electabuzz for the sake of completing the collection.)
Answer: HOENN
Explanation: There are four official Pokémon regions now: Kanto, Johto, Hoenn and Sinnoh, of which Hoenn is the third. Spin-off games like Colosseum and Ranger, of course, contain a couple of regions of their own.
Answer: YANMEGA
Explanation: In Stadium, certain nicknames would make Pokémon change their colors, and they mostly followed the pattern of reversing two parts of the Pokémon's species name - 'Sirpin' for Pinsir, for example. Yanmega's Japanese name is 'Megayanma' (although in the end, the secret nickname for Yanmega would be more likely to be just 'Megayan').
Answer: UNDERGROUND
Explanation: The treasure-digging minigame does resemble Battleship. The wording comes directly from my D/P changes section, so it could tip you off.
Answer: ODDKEYSTONE
Explanation: The main method to get the Odd Keystone is to talk to a Karate guy on Route 208, who will give it to you along with vaguely hinting at the rest of the method to get Spiritomb. However, Serebii.net's 'The Spiritomb Factor' section does not acknowledge the existence of this guy, most likely because it was made so early, instead telling you, 'You may find one lying about in Sinnoh, but it'ld be easier to find it in the Sinnoh Underground while digging, although it will be a bit rare.'
Answer: CHERUBI
Explanation: Koffing evolves into Weezing, which looks like bigger Koffing and a smaller Koffing stuck together. Cherubi, on the other hand, looks like a bigger cherry and a smaller cherry stuck together, and the smaller cherry disappears upon evolution (as it, according to the Pokédex, contains the nutrients necessary for the evolution to happen).
Answer: ODDISH
Explanation: Route 230 has both Gloom and Oddish, but the Gloom are much more common, making for trouble for those who prefer to raise the first stage of a Pokémon and then evolve it rather than having to breed.