according to the devs, Replays are not possible for the same reason Wifi isn't on the full build: because the game's unable to fully recognize certain inputs that the mod provides, resulting in desyncs.
and as for the wifi scene, the post above already pointed out while the PM menu said it's "officially" discontinued, there are unofficial servers dedicated for PM... and brawl if you actually play that.
setting up the latter can be done in one of two ways, one involves an app (which I don't find reliable)... the other is through a couple of modified setup files that a player named Rood posted somewhere on mediafire (which I have lost the links to).