I'm going to have to be honest on
Battle for New York, it's entirely a missed potential hour long special, moreso than
Showdown back in season 1; it's quite possibly the weakest of all the specials thus far and pales in comparison to
Annihilation Earth! later in the season.
So on paper, there's some very good potential ideas, among the most noticeable is the introduction to the Mighty Mutanimals for the first time on television, consisting of Slash, Dr. Tyler Rockwell (who has Tom Kenny voicing him now), the now alive Leatherhead and Pigeon Pete. In addition, we get the return to form of concluding the Krang arc, tensions with Leo and Slash, the raid in Dimension X, etc. I won't deny the story it wants to tell, but there are several glaring issues in this episode.
For starters, it's the Mutanimals themselves. Barring the recent comic book origin to tie strings together, what exactly causes them to join forces in the show alone? By this point, Slash and Leatherhead went MIA with the former going wherever after season 2 and LH presumed dead in
The Invasion. As for Rockwell and Pete, they feel randomly thrown and beyond brief dialogue explaining the joining under Kurtzman, there's no clue on how these guys formed especially with how they ended up where they are. Furthermore, why is it Leo is the only Turtle to despise Slash; shouldn't Mikey and Donnie have animosity towards Slash after being nearly beaten to death, especially Don? The characters aren't exactly clear in continuity interaction wise; without references to the Kraang back in season 2
Metalhead Rewired and
The Invasion it entirely feels like a mashup outside putting LH and Slash in due to being on the Mutanimals in the past.
Outside the main plot, why did Mikey screw with the retromutagen; though later proven in
Creeping Doom with his memory, it feels too much like a deus ex at this point. I can't tolerate Mikey's character changing on a weekly basis in the show, and though a great moment it's also one of the worst. Outside no sense of the mutagen set from the previous episode with Karai, Bebop and Rocksteady, why did Mikey think this was a good idea? I thought Michelangelo was a caring individual towards all and would want to save New York, not endanger all citizens from his idiocy.
Of all the main problems with this episode though, I personally feel is there was no buildup to set this event in stone and the rushed story doomed this episode. Beyond
Buried Secrets with the Kraang and brief appearances in
Serpent Hunt and
Return to New York, it feels like the entire "New York in peril" plot established vanished. A little more time should have been given to set up the stakes, whether it be a Mighty Mutanimals origin or a
"meanwhile in NY..... setting." Lastly, considering this is an hour long special, this felt especially rushed, which compared to a simple 30 minute episode makes no sense. Without any sort of idea of what happens outside the basics of
"Save the city",
Battle for New York feels like a rushed production relying on fans to watch from the beginning to get any involvement, ultimately undermining the entire drive of plot.
I won't undermine the positives though. After all, who doesn't love Gilbert Gottfried appearing?

The scenery of Dimension X is just as crisp from season 2 and the epicness is where it succeeds with suspense in conflict. However, it doesn't make up for a lack of substance nor buildup which this needed; as a result it feels the entire story rushed. If it were a 30 minute episode I understand, but not an hour long arc.
I know people might be curious why I put
Casey Jones vs the Underworld as my second favorite episode of the season; beyond it being a personal favorite, I nearly feel it contributes more to the story over the hour long episode before it. As the Kraang had almost no influence on the season outside the Triceratons at the very end and me being a sucker for gang war, Shredder's more of the primary focus with Karai and eventually the mind control arc, even with that arc of mixed reception at best.
Where I feel this episode succeeds is in addition to continuation, giving Casey some limelight and the introduction of Bruce L...... I mean Hun (

), the biggest strength is it setting up future events. It might not be on an epic scale, but it does play a little low with raising the stakes for future exploration down the line; the dynamic of Casey and Raph also gets a little more usage sorely lacking. Finally, who doesn't love references to the 1990 live action movie (
"The class is pain 101, your instructor is Casey Jones."). I guess what I'm saying is the episode's handling playing up Casey as over his head, but succeeds as the rogue vigilante he's known for in the franchise. Ultimately, it handles itself quite well on previous characters with motive and characterization, something Battle sorely lacked.
Then again, the episode is still flawed. Common complaints often stem from the animation of Shredder riding a motorcycle in addition to Casey being extremely over the line. Now the motorcycle I will admit is silly on Shredder (you want a limo instead?

) but Casey has proven to handle himself; he might not be a skilled warrior like the Turtles or April, but he does show a strategy side. He didn't entirely win as he merely got a surprise attack against Shredder, a cheap shot against Tiger Claw and merely beating Rahzar and Xever in a simple hit.
Granted though, Casey fighting underhand does offer the possibility of his own style; if he defeated Shredder then yes that's Gary Stu type writing, nearly in an identical manner to April's powers. However, the surprise shot does offer Casey playing wise something that yet to have been utilized due to the continuous triangle he's often involved in for the show and very rarely gets to shine. Simply put, he'd get his butt kicked still but like Batman, Casey planned because he knew he was screwed (until the Turtles arrived).
Tl; dr: The glaring aspects in
Battle for New York plot wise and from a lack of build up make it a severe disappointment among the hour long episodes compared to the surprises from
Casey vs the Underworld. Due to this, I place my vote towards the latter.