Now that I've gone over how super super important dialogue is to pacing, it's important to look at the pacing from a broader perspective. That is...
How is the game organized? This does depend on the kind of game it is, but the execution is generally the same. Pokemon games and most split up sections of the game through Gyms/Trials as an incredibly easy way to view the progression the player has gone through. In fact, most RPGs have a sort of division that separates scenarios, major plot points, etc. As someone who
refuses to use Gyms/Evil Villain Team (I still want to play Pokémon, but I'm very bored of traditional Pokémon games, and I simply make stuff I want to play)...
I think about the following in my works:
How is the game-play organized? This comes first after I come up with the plot, as I enjoy when story and gameplay are intertwined. If the story of a game is completely inconsequential to the game and the game is completely separate to the story to the point where you could've just wrote a book and game separately, I think the product as a whole as a great chance of losing engagement from players as well falling out of the world's immersion. In fangames, I try to make sure the story has doesn't end up having nothing to do with Pokémon or even the Pokémon universe and it becomes an RPG with an excuse for Pokémon battling once in awhile.
Gyms and Variations
Gyms are again a pretty simple way to show the player what their objectives are in the game, have a context within the game, and show how far they are in the game. Of course, the above criteria can apply to many things, so you actually don't need to have Gyms in a game to do the above! How would you space them out regardless?
I think it's important that the pacing of your game doesn't get too
predictable. This is a lot more difficult to pull off in a jam game or a rushed work, of course. If your game is a constant cycle or route -> gym -> gym leader not there cutscene -> route -> gym -> etc, the loop is exceedingly obvious and you'll run out of ways to surprise the player, knowing that no matter how good your story is, the progression is literally the same thing over and over.
I'd say to figure out more unique ways to introduce main plot points. Maybe introduce some new gameplay elements! In mainline, some towns don't have gyms. Others have the Gyms put on the backburner in a bit to explain some of the creation lore of the region (Sinnoh). This pretty much encompasses ANYTHING that is put in the game, including the evil team or something if you're doing that.
A gameplay loop helps determine what your player needs to accomplish to progress in a story or plot, but if they're just doing the same thing 8 times over with higher leveled mons, the pacing is "technically" fine, but it gets pretty repetitive.
An easy way to fix things up is the divide the gameplay unevenly. By doing this, you leave room to sprinkle in other subplots with a bit of a workout (such as infiltrating an evil team base) or give a break to the player by letting them cool off by introducing easier gameplay and perhaps have an area with a lot of misc lore, for example. Of course, this too, is an art, as making a segment too long or too short isn't ideal. Personally, I think it's better for something to be too short than too long. Introducing a gauntlet of a dungeon or trainer battles can get really exhausting very quickly, especially one after the other Even if the initial loop is fun, sticking too long to it will suck people out of the game.
Sidequests
The way most people tend to alleviate this issue is by introducing lots side-quests in the towns and sometimes the routes (more things to do in routes pls maybe :D), which technically does have an optional way to break-up the basic pacing and also introduce some world building.
A bit of a hot take, but I think side quests could prove to be less fluff/fetch-quests, and be more quality over quantity. Like, fetching a certain Pokémon or finding another NPC in another place in the city technically works, but that's also something that could be done in
any Pokémon game regardless of the setting. Perhaps a quest chain revolving around an altar in the village? Perhaps there's an entirely new zone underneath the city (with lots of rare items hidden??)? Stuff like this is more interesting and also less exhausting for pretty much
everyone.
If there's too much of anything, including side-quests, you'll
burn out completionists and
overwhelm the average player, who just wants to do what's useful. It's actually the reason why I prefer game-jam games than the All Pokemon 1-8, 60 hours of content, 30 Gym Leaders, Multiple Regions+Post-Game, super games, since the latter tend to break down and lose my interest over time with the enormous amount of features and incredibly long story. However, sometimes they're fun to play through, especially if they have a fun gameplay twist.