The LP petered out because the plot sort of petered out; I'd have had to grind through a bunch of dungeons just to get 'legendary shows up, legendary is recruited', and I lost the impetus to do so.
As for PMD2... well, I started an LP with the gimmick that I, personally, was the human sucked into the pokemon world. However, it went over like a lead balloon (it didn't help that the Something Awful forums are furry-intolerant and some folks took it upon themselves to dig up my Internet history and imply I was a pokefucker), so I wound up abandoning it. The forums have since put very strict anti-pokemon LP rules up, basically only allowing one guy to do narrative LPs, so I couldn't take another stab at it if I wanted to... which I don't. I'd started the second LP blind, and playing through the game on my own made me realize that it's a worse game than the first in measurable ways, which eventually put me off.