Btw the answer to your hangman thing is Rayquaza legendary type dragon&Flying, founded in ruby/sapphire/And commonly know emerald show in the movie destiny deoxys
New topic :3 Why Ash can't grow up his Pokemon too strong?;
Idk... i believe he allows his pokemon to grow at there own pace (Aside from when he has a grudge) Sadist thing is most of his evolving pokemon were fire typings, disproving the factor that in the shows Ash doesn't evolve his pokemon this means his pokemon are strong in a sense, although to be strong one would ev train(Hopefully everyone understands what this is...) but the show never mentioned Ev training but it seems to still be valid in the show, i digress(Quiet a bit) As it stands Pikachu is strong, just every time Pikachu goes to a new region he's reset to level one in a sense removing his op abilities (Aside from Electro-ball, and volt tackle and of course... iron tail -.-") Every time Pikachu either gain more power or is on par from his version one self, as for his secondary pokemon most of them are well... i guess they'd be considered placeholders for his original pokemon(I Get this idea from the factor that in both the unova region and battle frontier his original team (Or some of them) had a comeback showing how much stronger they have gotten, so this topic is kinda actually filled with holes... I mean Charizard fought Articuno in battle frontier and his team went against regi steel, ice, and rock... so his team is actually very,Very,VERY strong to go against legendaries.(Also this is my opinion, i know articuno, and the regi's arn't what they use to be)
(Sorry if i spammed or if you expected a small answer XD)