1. Okay. I get that it's in the first poster. But, unlike Dragonite, Gengar and Lucario - it's actually quite hard to spot and its depiction in TINY.
Ash and Dragonair? What? A lot of promo? Please provide evidence, because I have never EVER seen any promotional material with Ash and Dragonair specifically.
I agree on Gengar (solely for the Ghost-type and the potential that it MIGHT Gigantamax) and Lucario. In Lucario's case, it also adds the possibility to showcase Steel Beam more often (and it fighting-style is vastly different to Melmetal).
2. No, never heard of any such speculation. Phanpy as a make-up for Rhyhorn is also reaching as there was never such a reference made during the actual time Phanpy was on the team. Why couldn't Heracross compensate for both if this speculation is indeed true? xD Just because something is efficient suddenly means it isn't fitting a selfdefined theory anymore? xD Where was Lapras' replacement then by the way? Or a compensation for all the Pokémon Ash wanted to capture in Kanto that he never came around to? No, you haven't convinced me that there was widespread speculation for Ash and Tyrogue (nor Dragonair while we're at it).
3. I saw you already reacted to someone about this. It's just a game thing mostly. That small group that can't breed and aren't legendary - those are the group canonically classified as the babies (whether they are lvl1 or lvl100, or heck 10 years old). That doesn't mean that we still can't have a baby Squirtle, but that doesn't mean it belongs into that group - because in the games it can breed as soon as it hatches.
1º) That depends on the poster's quality. I mean, way more difficult to pot in the poster in Meltan, next to Mimikyu in the Alola's zone. There was quite a lot of promo of Ash with Dragonair, but it had to be removed when the episode of the Safari Zone was banned; as that's where Ash and Dragonair started to appear together then. We could also count the scene at the original opening where Ash and Pikachu where on Lapras while a Gyarados and a Dragonair appeared in front of them. And I don't think Lucario will learn the Steel Beam. I think the Metal Claw (which looks like Wolverine's claws) will be used instead.
2º) You might not have realized, but for a long time, turns out that when people thought that Ash would capture a Pokemon and failed, he instead got a similar one in the next Generation. (By the way, Glalie was like Lapras' replacement for being an Ice Type for Ash). That's one of the clues for people especulating about Ash getting Tyrogue. If you need examples of what I said about "compensations", there are these:
+ Phanpy/Donphan for Ash because he failed to catch Rhyhorn.
+ Glalie was for Ash because he lacked an Ice Type after freeing Lapras, who by the way, it momentarily returned in the previous Generation.
+ Gible was to compensate that Ash didn't capture a Trapinch/Vibrava/Flygon, which is a Ground/Dragon Type too.
+ Torterra can be a compensation for Venusaur and Blastoise, as Bulbasaur and Squirtle still haven't evolve to this day. Torterra physically looks like Venusaur and at the same time, it is a "tortoise" just like Blastoise.
+ Both Infernape and Pignite can be partially compensations for Primeape, as one is a Fighting Monkey and the other one is a Fighting Pig, as Primeape is a weird mix between a monkey and a pig. Not to mention their Fire type can be a reference to the Pokemon that allowed Ash to capture Primeape.
+ Litten/Torracat/Incineroar might be a compensation because Ash didn't capture Litleo/Pyroar in Kalos, as he replaced a lion for a tiger.
+ Finally, Trevenant and Pumpkaboo were too Pokemon that were especulated for Ash to capture because of their Grass type and their Ghost Type; but instead, Ash got Rowlet in Alola, which evolves into a Grass/Ghost type too, Decidueye.