I wonder. Is NT a good game to jump into that fighting series with?
It's a fairly different beast from the first two honestly due to being more focused on being a tag team arcade game than the one v one RPG fighting game like the first two are focused on.
The first two are more focused on gaining levels and equipment and moves and customizing them while NT each character has some things that can be customized but otherwise are more static in their roles as they are more designed to provide teams with a specific gimmick.
The downsides for the first two in that it's highly unbalanced and shallow a lot of the time and most characters have one set up that is considered viable anyway, making a lot of its customization kind of moot a lot of the time on top of equipment just being taken out entirely for actual multiplayer stuff. Also some characters favor having a gimmick that doesn't actually make sense for how the game plays. Firion for example is heavily designed around ground combat in a game where players can jump and stay in the air near infinitely, the character's gimmick runs counter to how the game works and thus ends up struggling. It's got a lot of focus on single player stuff like a bigger story mode, arcade mode, and dungeons and stuff. Also due to how much invincibility dodges get in the game high level matches can become dodge fests.
NT designed as a 3v3 has the issues of lacking much of the customization and being more team multiplayer focused. It's generally better balanced but the story mode is nowhere near as extensive as previous games while kind of demanding you needing others to get the most out of it. Think it's been getting some more single player stuff lately but otherwise is kind of light on single player content. Also lost its super moves due to its more arcadey focus. Also is a heavier feeling game by design. Each character can only dash around in the air so long before needing to hit the ground again to recover stamina for it which makes it so you need to plan your approach more.
Each has certain strengths depending on whether at the end of the day you prefer single player content and matches or multiplayer and team matches. Dissidia 012 is a good one to get for your more casual story driven fun, NT for more balanced arcade team fights.