So I've been playing through the Black & White duo (Playing the Black Version) of games for the second time, and i've come across a Nuzleaf for the first time. However, when I first played I had used a Breloom instead, so now I've been rethinking my Pokemon team and choices, and so instead of using Breloom i'm going to use the Seedot line this time. So I was wondering if I should catch another Seedot or Nuzleaf to get another nature (since i've never been a guy whose understood natures in Pokemon) if Relaxed might not be worth it? By the way my Nuzleaf is level 41 and I don't wanna waste my leaf stone just in case.
If you want to use your Shiftry in the Battle Subway (the trains) or in battles against other people, then you should probably not be using Shiftry at all. Even if you got a Shiftry with a good nature, it would still be weaker than a Tyranitar with a bad nature. If you want to use the Shiftry for just about anything else, like the Battle Subway (the sandwich restaurant), then its nature shouldn't matter.