>>41548522>gen 4This is where I think they got a bit carried away. Dialga, Palkia, Uxie, Mesprit, and Azelf are all important to the central plot. The mythology is omnipresent in Sinnoh - from Eterna City to Celestic Town to Canalave City, there's all sorts of shit to be found. Regigigas sits in a prominent temple in Snowpoint, Cresselia is the centerpiece of a quest in Canalave, the only legendaries who were really hidden were Heatran and Giratina. I don't believe either had much in the way of lore in DP - Giratina may have been one of the most interesting legendaries ever, before Platinum came out.
>gen 5Interesting one. The tao trio take center stage, being the object of the plot and all that, but like with gen 3, none of the other legendaries really matter to the plot. The musketeer dogs don't have much lore, IIRC, but the kami trio have a fair bit given to them. Kyurem was somewhat wasted - it comes across as a bit of a mindless monster in the games. It might have been cooler if, in B2W2, instead of being controlled by Team Plasma, it kept breaking free from them and trying to find Reshiram or Zekrom to merge with them itself.
>gen 6Not a very good implementation. Xerneas and Yveltal are limited to their games - I don't believe you even hear about Yveltal in X, for instance, whereas RS told you about both Groudon and Kyogre, and DP told you about Dialga and Palkia, and BW showed you both. Zygarde is just present - no lore whatsoever.
>gen 7The Tapus were done well. You see Koko early on, you always hear about what the Tapus have done over the years, then SM ends with you battling Koko for yourself. Only real issue with them is how retarded their shrine puzzles are, but whatever. Necrozma was interesting in SM, and actually got better with USUM. Solgaleo and Lunala are weak though. Everybody reveres the Tapus, but these two don't have much presence in the lore of Alola, imo.