If you could only select one pokemon game for the DS to play.

[realworksuks]

I have a long trip coming up and trying to think of what to play. I only played Pokemon blue, and yellow way back in the day. I am thinking maybe play a Pokemon game. With that said... which one should I play if I only intend to ever play one version?

[SCD]

For the DS games, I recommend you should try and play either HeartGold or SoulSilver, they're really good remakes of the Gen 2 games.

[Supergamerguy]

For the DS games, I recommend you should try and play either HeartGold or SoulSilver, they're really good remakes of the Gen 2 games.

I wholeheartedly second the HGSS recommendation. I would also recommend trying out Black 2 or White 2. Honestly, you can't go wrong with any of the mainline DS titles.

[PowerPanda]

I would rank the DS titles as follows

5. Diamond/Pearl
4. Platinum
3. Black/White
2. Black 2/White 2
1. Heart Gold/Soul Silver

That being said, one standout feature of Black/White is that the pokedex is all self-contained, without containing pokemon from other regions or previous games until the postgame. That gives it its own unique charm.

[FAST6191]

My dislike of pokemon is the same as anybody that has manned a hacking section, emulator support section or similar over the years. Pinch of salt then recommended if asking such a question around here or similar places.

To that end the answer if is course Pokemon Dash.

More seriously pokemon is basically the same game whatever version you play, give or take a minor mix up in the very latest titles.
To that end I might instead suggest mystery dungeon (some ponder whether its GBA counterpart is better, and it is a notion I could stand to hear out), conquest or ranger (though ranger is by far the weaker of that bunch).
Bonus that way is you get a nice intro to the Mystery Dungeon/Fushigi no Dungeon and Nobunaga's Ambition franchises if you wanted such a thing (both legendary franchises in Japan that seldom make it out, even putting aside my seething hatred of pokemon there are better offerings in both but at the same time they are not bad by any means).

Will also have to have a look to see what became of the source code leaks that happened as part of the gigaleak. Would have expected a bit more to filter out of things by now.

[EvilJagaGenius]

Are hacks on the table for this discussion or no?

I second Mystery Dungeon, I haven't gotten to the DS games but Red Rescue Team is fun stuff.  This Reddit post has a list of Explorers of Sky hacks, I have in some old notes that Azure Sky and Explorers of Alpha look like good QoL upgrades.

My dislike of pokemon is the same as anybody that has manned a hacking section, emulator support section or similar over the years. Pinch of salt then recommended if asking such a question around here or similar places.

To that end the answer if is course Pokemon Dash.

Alternatively, Pinball in the GBA slot!

[PowerPanda]

Well, I mean, the answer is Nexomon Extinction, but it's for modern systems, not the DS. It takes the Pokemon formula, but allows you to tackle its zones and challenges in any order, scaling the toughness of the mons according to what you've already done in the game. It has a custom new game mode that gives you official randomizers and nuzlockes, its legendaries are tightly integrated into the plot, and it has the most epic final battle I've ever seen in a monster collection game. Seriously, I don't bother with new Pokemon games, but I played the heck out of Nexomon.

[Bonesy]

Normally I'd say HeartGold/SoulSilver but today I feel like suggesting Black 1/White 1. The entire game is all-new pokemon until post-game and you technically only need HMs once (cut at one point). Might be a good experience for you.