Applejack didn’t have much to accomplish other than I guess finding out the mystery of her parents. She was never one to care about long term goals and is just content with just running the farm and keeping it afloat.
Pinkie’s accomplishment was fully accepting her destiny of being a party pony and making others smile as shown with The Last Laugh. Frankly I thought there could’ve been a bit more but I thought it was satisfactory enough.
Rainbow Dash already had hers accomplished, it just mostly went towards her flaws and exaggerating them. It got old fast and did great disservice to her, but by the end she grew as a character in a way.
Rarity was already done by around Season 5 or so, there just wasn’t a whole lot to work with her after that. Probably more on expanding her relationship with her sister or her handling the stress of owning three boutiques.
Twilight Sparkle in my opinion did change a whole lot throughout the series but by around the end, she already hit her peak and there was no way to go but down.
Fluttershy definitely did evolve and they did make sure to note that it stuck, but the bad part is that it came at the expense to others and even to her own character.