>>25226621It used to be a tough choice between all the main 6 hugging each other at the end of Cutie Mark Chronicles when they realized they were friends they even met each other and At The Gala in Best Night Ever for how happy they were to finally be carrying out those dreams after thinking about it all season.
Moondancer breaking out of her shell was close to topping those, but I'll have to agree with the other Anons calling the CMC finally getting their marks in CotLM the new happiest for them. The bookends of the CMC starting with Diamond and her being the final cause of them getting those marks, the amount of time it took and how overjoyed they and everyone around them were when they got them, and the fact that it was something like what they got literally destining them together as friends helping other ponies realize what their marks are for was too good.
Maybe I'm a sappy faggot for going into detail like this, but them getting their marks after giving friendship to another pony they used to hate when they needed it most and realizing they care more about helping others and staying together as friends than earning their marks seems like one of the shining moments for the show's theme of friendship being magic.