Here's a list of stuff to get:
- Pokemon Mystery Dungeon: Gates to Infinity
I personally would hold off on Gates to Infinity.
As Mystery Dungeon games go, it's one of the weakest. Despite being Gen 5, and therefore having access to 649 pokemon, the game only uses 144 Pokemon, the large majority of which are Gen 5 pokemon (yet not all of them).
The storyline was good and entertaining, but it felt considerably shorter than the previous installments.
Furthermore there was much less of the game to play after you'd completed the main storyline.
In the previous games there were usually a few more shorter storylines to play after your main game, which were often linked to some legendary Pokemon. Gates to Infinity lacked that.
Overall, Gates to Infinity was a bit of a let down. It very much just felt like an early test for a 3D 3DS Pokemon game ahead of Pokemon X/Y.
If you are a fan of the series and want to continue that fanhood, then go for it.
And if you're new to the series the game, as it is short yet fairly charming, can be a decent starter game to the series.
But, it's more expensive than buying an older game, and it's actually easier than older games (Hunger, a large factor in gameplay which is there to prevent you from taking too long, is missing for almost the entire game until your final few stages).
If I could recommend a better game, it would be to look for a copy of the DS games Pokemon Mystery Dungeon: Explorers of Time/Darkness/Sky.
The game is longer, has every Gen 4 and below Pokemon (bar Arceus).