Special thanks to opaltiger for helping me create this crossword!
Theme: Ponyta
Answer: HOUNDOOM
Explanation: The Pokédex entry for Houndoom in Gold (and LeafGreen) says that if its flames burn you, the pain will never go away. Houndoom relates to the theme because it has Flash Fire, the same ability as Ponyta, as well as being a Fire-type like Ponyta.
Answer: HOWL
Explanation: Arcanine and Houndoom learn Howl. Connected to the theme because it relates to them and they connect to the theme. :o Yes, this makes perfect sense. Shut up.
Answer: BLAINE
Explanation: Blaine has a level 40 Ponyta in Red and Blue (and thus FireRed and LeafGreen), but in Yellow he only has a Rapidash.
Answer: TAKEDOWN
Explanation: Ponyta learns Take Down at level 43 in R/B/Y, 34 in G/S/C, 31 in R/S/E/FR/LG, and 28 in D/P. Add those together to get 167; divide that by five to get 33.4. Yes, quite literally the average level.
Answer: BURNHEAL
Explanation: Before you battle him, Blaine says something to the effect of, 'Wahaha! You better have BURN HEALs!' Blaine has a Ponyta, and Ponyta burn things, relating it to the theme.
Answer: POLIWAG
Explanation: In the animé episode 'The Ultimate Test', a swirl is shown and Ash guesses it is Poliwhirl, only to find that it is Poliwag's because the swirl changes directions when it evolves. Poliwag's Yellow version Pokédex entry, however, says that the direction of the swirl changes depending on the area it's in. It connects to the theme because they're both Kanto Pokémon. :o Well, that and the fact Ponyta was in the quiz in that episode as well - a flame was shown which turned out to be from Ponyta.
Answer: FIRESPIN
Explanation: Fire Spin is move number 83; Farfetch'd is Pokémon number 83. It relates to the theme because Ponyta learns Fire Spin.
Answer: KANTO
Explanation: Outside of Japan, there was no mention of the region's name in R/B/Y - only G/S/C told us the region was called Kanto. (It was shown when viewing the Town Map in the Japanese version, however, and in Super Smash Bros.) Ponyta originated in Kanto.
Answer: BOUNCE
Explanation: The list is the list of Pokémon that can learn Bounce - which, in the third generation when the move was created, is limited to the Ponyta family and the Spoink family.
Answer: LAVACOOKIE
Explanation: Well, Ponyta is a Fire Pokémon, and it's a 'lava' cookie.
Answer: HIJUMPKICK
Explanation: The FireRed Pokédex entry for Ponyta says it can 'clear Ayers Rock in one leap' (the proper name for the rock is Uluru). Ponyta can also use some Fighting-type kicking moves (Double Kick and Low Kick, although Low Kick was event-only). It can also jump high, so why not let it learn Hi Jump Kick?
Answer: STEALTHROCK
Explanation: Stealth Rock inflicts double damage (1/4 of total HP) on Pokémon that are weak to Rock every time they switch in, and Fire-types like Ponyta are weak to Rock, meaning Stealth Rock makes things a bit difficult for most of them.
Answer: BUTTERFREE
Explanation: Poisonpowder is the numerical equivalent of Ponyta; that is, it's move #077, while Ponyta is Pokémon #077. Butterfree learns Poisonpowder, along with Stun Spore and Sleep Powder, at level 12.
Answer: INFERNAPE
Explanation: The Ponyta and Chimchar lines are the only Fire-types in the Sinnoh dex.
Answer: NATURALGIFT
Explanation: Come on. Ponyta is a burning horse.
Answer: NINETALES
Explanation: The Yellow version Pokédex entry for Ninetales says that according to legend it was created when 'nine noble saints' were reincarnated as this Pokémon. The Sapphire Pokédex entry, on the other hand, claims it was created when 'nine wizards' possessing 'sacred powers' merged into one. So which one is it? Ninetales is the same type as Ponyta and also has the Flash Fire ability.
Answer: HITMONLEE
Explanation: Hi Jump Kick can be said to be Hitmonlee's signature move, and Hi Jump Kick is a word in a Ponyta-themed crossword.
Answer: HEALBLOCK
Explanation: 26 across revolves around the move equivalent to Ponyta, Poisonpowder, which is move #077. Move 377, on the other hand, is Heal Block.
Answer: BAYLEEF
Explanation: Bayleef learns Solarbeam at level 54 in Diamond and Pearl. Ponyta has been able to learn the Solarbeam TM since Ruby and Sapphire. Solarbeam is a good move for a Fire-type to have, since it works with the Fire-empowering Sunny Day and is super effective against all the types Fire is weak to, but unfortunately Ponyta's Special Attack isn't that great.
Answer: RUNAWAY
Explanation: The item Smoke Ball, when attached to a Pokémon, allows it to escape from any wild battle. So does the ability Run Away, however, so with the ability there is no need for a Smoke Ball if running away is your thing. Run Away is one of Ponyta's abilities.
Answer: WEEPINBELL
Explanation: Weepinbell is Pokémon #070 in the National Pokédex. Ponyta is #077. 70 * 1.1 = 77.
Answer: FLAREBLITZ
Explanation: Ponyta is a Fire-type Pokémon, and Flare Blitz is the only physical Fire move it learns naturally.
Answer: NIGHTSLASH
Explanation: Night Slash is the only STAB move Stunky learns (the other Dark and Poison moves it learns being non-damaging), and Stunky is found on Route 214 in Diamond, where Ponyta is also found. Yes, this makes perfect sense. <_<
Answer: GYARADOS
Explanation: Gyarados is a Water Pokémon, and Water moves used to be special, while Gyarados has a much higher Attack than Special Attack. Ponyta also suffered from the same thing before Diamond and Pearl.
Answer: PINECO
Explanation: All of those are true. Both Pineco and Ponyta have 50 base HP, the first letter is P, and the third is N.
Answer: RAPIDASH
Explanation: Rapidash evolves from Ponyta. If you did not know this already, you should not be attempting the crossword.
Answer: ARCANINE
Explanation: According to Yellow, Arcanine is a 'legendary Pokémon in China'. Arcanine is, like Ponyta, a Fire-type and also shares the ability Flash Fire with it.
Answer: OVERHEAT
Explanation: White Herb is often attached to Pokémon that use Overheat to negate the Special Attack drop, but how the heck does a herb survive an attack like Overheat? Related to the theme because Ponyta learns it.
Answer: REVERSAL
Explanation: This kind of joke is called a 'Russian Reversal', and it doesn't really have anything to do with Ponyta (except that Arcanine and Hitmonlee, who are also in this Ponyta-themed crossword, both learn it), but the reference was too good to pass up. Sorry.
Answer: HOENN
Explanation: Hoenn is the only region (to date) that Ponyta cannot be found in.