I was thinking of getting it, but do I really need it?

no but if you want to you could...

I only got it because I had just gotten Wi-Fi and had some money to spare and also there weren't any good wii games at the time

It seemed to similar to Pokemon Stadium 2 minus the wi-fi to me.
already had Stadium 2, so why get PBR? is what I thought.
Now I don't have the finances for it, and I am currently in college...yes, right now I am literally typing this on my laptop sitting on campus.
So I can't really say if it's worth it or not, but that was my reasoning if it helps.

In my opinion, it's not worth a $50 price tag. I would say it's only worth about $30-40. The Wi-fi feature is the best part about it. The ability to customize trainers is pretty cool, too. Sure you only get 6 designs, but I like the ability to change the way you look. I would say that if you could find it for a good price, get it. If you can't, at least rent it. If you rent it, you can decide for yourself if you want it or not.

Ah. This is a good question.

Well, in the end, Pokémon Battle Revolution is only worth it as a way to get exclusive Pokémon and for WiFi battling. The story mode is a bit of a sham and there's not much to do once its over. The ability to make a custom avatar is nice, and it gives you a nice sense of the fact that you're actually the one battling.

However, it needed MUCH more work before it could be something like Colosseum or the Stadium games.