@
KingBro1 BN1 is very dated, but if you have the time, play it. Just use a guide to navigate the net and dungeons for the first BN game. In fact, you could probably do that for every BN game since the dungeons are weirdly designed mazes and that can get really annoying.
BN2 is definitely better than 1, but I do suggest playing the first game. 1st game has some fun world building and story that sets things up. Basically everything in the first two games actually sets up the conclusion of the story in 3, so I suggest playing it in order. The battle system is fun, but I wouldn't play the game just for the battle system if you're doing it for a single player experience.
If I did a quick run down on the series, it'd be
BN1: Everything begins here. Dated battle system, a really fun and contained story. I don't replay this game unless I want to revisit the story. Use a picture guide for the maps to save yourself trouble.
BN2: Outdoes the first in every way, but you appreciate it more after beating the first. Really fun story, my favorite scenario of the 6. Better battle system by giving Styles that depend on how you play. Adds a lot more diversity into the mix. The gameplay is still horribly broken and not balanced with its Program Advances.
BN3: Middle of the story isn't as fun as 2, but the ending ends off the arc in a bang. Battle system is a lot more polished, but still isn't as balanced. Navi Customizer is introduced which gives players so many options on their character.
BN4: Worst story, hands down. The 3rd game basically concluded the story, so the fourth game starts off with some weird new stuff and boring scenarios. The good though is that the battle system actually shines and gets competitive. Best battle system of the 6 games if you were playing competitively with people (imo).
BN5: Better story than 4, but still a pretty bad game. Adds some new features, but they end up just being a chore. I absolutely broke the game in this one in Team Colonel. With the right setup, I basically had an 70 percent chance to deal 2000 unavoidable damage in the first few seconds lol
BN6: Only played this in Japanese. I never played this multiplayer, but I enjoyed the story. Best story out of the last three games, and the ending was nice for me. Especially since I was Lan's age or so when BN1 came out, so it's nice to see how it progressed.