Firstly, Meloetta is gone from the Anime, the episodes it appeared in have aired in both Japan and the dub has been shown. You're making it sound like they are still doing stuff with it, they aren't.
Originally Posted by *futachimaru*
Secondly, it only appeared in 16 episodes, basically half of what you said, even more, most of those episodes weren't "dedicated" to it. Here, I'll even go over each:
Movie Showdown! Sortie, Unova Defense Group!!-Debut of it, only had like once scene focused on it, rest of the episode was focused on Pokéstar Studios.
Rocking the Virbank Gym! (Part 1) Fierce Fighting at the Virbank Gym! VS Roxie!! Part 1-It appeared, but no focus at all, it was just there hiding away following Ash, the episode was focused on Ash's gym battle.
Rocking the Virbank Gym! (Part 2) Fierce Fighting at the Virbank Gym! VS Roxie!! Part 2-Same as above.
All For The Love of Meloetta Sing, Meloetta! The Melody of Love!!-Now this episode was actually focused and dedicated to it. However, there was still other stuff in focus of the episode, such as Cynthia.
Piplup, Pansage, and a Meeting of the Times! Piplup VS Pansage, the Magnificent Battle!!-It got some screen time, but the episode wasn't about it, Dawn's return is what was the focus.
Expedition to Onix Island! Survival on the Island of Onix!-It showed of it's other forme, but other then that the episode wasn't about it.
The Mystery of the Missing Cubchoo! Connoiseur Detective Cilan! The Mystery of the Lost Cubchoo! -Nothing. It appeared, but in no way was the episode about it at all, it was about finding a lost Cubchoo.
Iris and the Rogue Dragonite! Iris and the Roughneck Dragonite!-Helped calmed down Dragonite, episode still wasn't about it at all.
Jostling for the Junior Cup! The Junior Cup Gets Underway! Dragonite VS Beartic!!-Tournament focus, pretty much didn't do anything the entire time throughout the tournament.
Battling Authority Once Again! Power Battle! Iris VS Dawn!-Same as above.
Ash, Iris and Trip: Then There Were Three! Ash, Iris & Trip's Final Battle-Same as above.
Goodbye, Junior Cup - Hello Adventure! The Junior Cup, Site of Partings and Encounters!-Same as above.
The Road to Humilau! Humilau Gym Battle! Mantine VS Samurott-Nothing really happened with it, episode was more focus on Ash and Cameron bonding and Cameron having his final gym battle.
Unrest at the Nursery! Pokémon Nursery School Uproar! Rufflet & Vullaby!-It calmed some Pokemon down, nothing else, episode was focused on Rufflet and Vullably. Throughout some of these episodes, Team Rocket was stalking Meloetta but even that was a small scene in each episode to lead up to the climax.
Meloetta and the Undersea Temple Meloetta and the Underwater Temple!-Climax, of course it's focused on, it is important to the plot. Despite this, there was still other stuff going on.
Unova's Survival Crisis Advance of the Therian Formes! Unova's Greatest Crisis!!-Same as above. It leaves the show at this point.
As for the Pikachu short, yah it got one, and guess what, it didn't get a movie at all, so this was all substitution for that, and in fact, was something new that the writers did, a Legendary Pokemon has never followed Ash around to my knowledge(Unless you want to count Ho-Oh, even though the situations are far from the same). So much for "repetitiveness".
Finally, I'm closing this. Pretty much for the reasons I already went over(It's no longer in the Anime, and it didn't get nearly as much as you made it out).
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