Wait-wait-wait! If the Time Machine was existent in GSC to communicate with RBY trainers; wouldn't that ALSO imply that there'll be a new moveset? Think about it. Remember back in GSC, someone, I can't recall who, mentioned that you can only bring Pokemon into the trade room that existed in RBY's trainer's timeline AND only have moves that were current in that timeline? Well, if that logic is put into place and there is indeed a Time Machine in HGSS, then I guess it's safe to say that there would be new moves.
What do you think?
On another note, I would think if the Time Machine wasn't going to be implemented, then there HAS to be some Pal Park inclusion. The only reason, the PURE reason a Time Machine would exist is to communicate with trainers of the past, which would mean trainers of Kanto and Hoenn. (I mention Hoenn because of that quest we're sent on to recover the Ruby and Sapphire for the Trade Machine on One Island. Therefore implying that Kanto's and Hoenn's events happens at the same time.) This would exclude Sinnoh trainers being that the Red Gyrados incident was mentioned all over that game. With that, we can assume that Sinnoh would just have a normal trade station. However, Kanto and Hoenn would indeed need a Time Machine being that events have occured over that three year period.
Although if no new moves are going to be released exclusive to this game, then we can safely rule out any possibility of a Time Machine. If is the case, then there HAS to be a Pal Park addition.
Lastly I would like to include is -- we all remember what the GSC Time Machine did, TRADE with Pokemon that existed in between RBY. Well, as we all are aware of, Nintendo never made such an adaption that DS cart Pokemon games can trade with GBA cart ones. The most was SEND GBA Pokemon to DS. Being aware of all these functions -- then for sure there'll have to be a Pal Park addon.