Good points. Telling me to give up on Lip in Smash Bros., though - even now when it's looking increasingly unlikely that she'll be playable - is like telling the sun not to be hot. Maybe I secretly like setting myself up for disappointment. But yeah, I see where you're coming from.
The "character not being in any recent games" argument doesn't hold much water to me, considering the Ice Climbers, but a case can sadly be made for it. All of the newly revealed characters for the fourth game besides Mega Man have seen new games in their series come out in the past two or three years. I'm totally on board with a retro slot goin' to her though, as unlikely as that's looking.
I like the idea of a Western campaign for a new PDP game, but getting the attention of such a big company as Nintendo would be really tricky - especially considering, given its obscurity outside of Japan, how many people would be on board with it (hint: not many). I'd expect an "I like your enthusiasm, but we have no plans for it at this time [read: ever]" response at best. It's a real shame: the Panel de Pon universe and its characters have some wonderful storytelling potential and deserve a lot more recognition than they've ever gotten, plus it would mesh extremely well with the neo-feminist girls-need-role-models wave that Friendship is Magic started... but Nintendo hates, perhaps is even ashamed of the series for no good reason, so for now at least the burden of creating new adventures in said universe rests squarely on the fans. (But I can name maybe... five? current Western PDP fan works off the top of my head, four of which are taken seriously, one of which is dead/dying, and three of which are mine - and of those three, two haven't even gotten off the ground yet. Being a fan of this universe is hell.)