Skullpanda said:
Well...it's more towards your gaming style, really. Personally, I prefer the offerings from the PsP compared to Nintendo's library, but that's just me. The main offerings from Nintendo, however, are largely based around the target audience for the DS, i.e.: Little kids.
And this is where I stopped reading. Seriously, in the days of Viva Pinata and Little Big Planet, I think we can get over the "Nintendo = Kiddy" stereotype.
Anywho, as for the OP, if you're already a fan of the Pokemon series, then go with the DS. It has just as many (if not more) good games compared to the PSP. On top of that, it's cheaper, and while it lacks some of the features that the PSP has, your iPod that you mentioned probably covers those bases anyway.
Some people might argue that every game on the DS is "too gimmicky" by forcing the stylus. Well, after I'd owned my original DS for a year or two, I was relieved when I finally bought a game that DID make heavy use of the stylus. So honestly, the "gimmicky stylus" thing is more propaganda than fact, likely created by Sony fanboys. There are just as many games that use almost exclusively the D-Pad + Buttons as ones that make heavy use of the stylus.