In recent Pokemon games, you have been able to use a few Pokemon as mounts in order to travel faster, or replace HM moves. Players haven't, however, been able to choose which of their companions they can ride for faster travel, and those that look like they'd be perfect for the role are ignored. Only Pokemon Let's Go let you pick what Pokemon to use as mounts, but it was still limited to a select few.
Instead, in many games, players are given bicycles. In a world full of fascinating creatures that can fly, burrow, teleport, and climb waterfalls, there are so many other potential ways of getting around with their help. Pokemon Scarlet and Violet had the right idea by making your fastest transport a Pokemon. With more games putting more Pokemon in the overworld, perhaps the day isn't far off where you can choose which Pokemon to travel with. Here are some suggestions.
10 Rapidash
Rapidash is the original equine Pokemon. The flaming-maned speedster is built for quick travel, yet only in Pokémon Let's Go can you actually ride Rapidash as a mode of transport. No mainline Pokemon game has, to date, offered this chance.
Not only is the idea perfectly logical, there is even an excellent episode of the anime based on Pokemon racing, and Rapidash is one of the creatures utilized for the purpose. Available since the first generation, it feels like a missed opportunity not to allow players to take to the roads with a burning steed. On top of everything else, it would be wonderful Kanto fanservice.
9 Tentacruel
Who doesn't want a small, manageable kraken of their own to travel the vast swathes of water in the Pokemon world? Every game has its water segments. In the early seasons of the Pokemon anime, Tentacruel was portrayed as an oceanic monster. Often oversized, it could take down boats and attack cities. In-game, Tentacruel doesn't have the size for such fearsome feats, but its sheer prevalence in the watery routes of the games (along with its pre-evolved form, Tentacool) suggests that it might not be difficult to find one willing to give the player a ride. Like Rapidash, it would also be an excellent throwback reference.
8 Torterra
Riding on Torterra's shell would be an effective and safe way of engaging in travel. Granted, you wouldn't get anywhere particularly fast, but it would be an interesting way of creating a safe zone in what might be a harsh and/or hazardous landscape, like a desert. Not all mounts have to be about speed, and using Torterra's unique design to facilitate dangerous trips would be a good way to make use of more than just a Pokemon's stats.
It could also potentially smash obstacles that would otherwise bar your way, as in the brief segments in which Rhyhorn are ridable in the series.
7 Scolipede
Bug Pokemon don't get the same spotlight as other types. They're sorely underrepresented in the higher ranks of competitive play, and among Legendary and Mythical Pokemon. They need a little attention. Making Scolipede a ridable Pokémon would be a good start. As Bug Pokemon go, it's one of the largest, and is of substantial enough size to support a rider. Scolipede would be perfect for traversing tall grass. With its tall neck it could keep the player high above the grass, and let them avoid encounters if they so wished. It'd be more interesting than just buying Repels to evade the attentions of wild Pokemon.
6 Corviknight
Pokemon Sword and Shield came so close to greatness with Corviknight. Instead of using the fly HM, players would hop into baskets carried by Corviknight to fast travel via sky taxi. At that point, why not just cut out the basket and let players ride the Corviknights themselves? It's one of the most formidable-looking Flying-type Pokemon of any generation, and being able to fly over the Wild Area on Corviknight's back, rather than using a basket, would be much more fun. Corviknight also went on to excel itself in battle, with its Steel and Flying typing and solid offensive and defensive capabilities.
5 Tyrantrum
Anyone who grew up watching Jurassic Park would surely jump at the opportunity to have a dinosaur mount, in any game that could make it a reality. Tyrantrum would be perfect for that purpose, it looks the part of the iconic Tyrant Lizard it's based on. With Pokemon Legends Arceus letting you travel back in time, and Scarlet and Violet delving into the concept with its futuristic- and ancient-inspired variations on Pokemon, a series release taking place when all the fossil Pokemon were alive may not be as outlandish as it sounds. In a game like that, taming and riding a creature like Tytantrum would fit right in. Even without such a mechanic, the long-running fossil revival mechanic means that Tyrantrum could potentially serve as a mount in contemporary times.
4 Milotic
In every game it's appeared in, Milotic has been heralded as a creature as rare as it is beautiful. It tends to be suitably difficult to evolve Feebas. In the generation this evolution line was released in, diving underwater was another method of travel in the game, and Milotic would be great for helping players journeying underwater.
Like a majestic sea serpent, finding it could be as much a story point as acquiring the HMs have been in some games previously. It would also just be nicer to see, given how rare the Pokemon is normally. It's similar to the first generation's Lapras, which has served such a role on the surface of the water, but doesn't get the same attention.
3 Steelix
Steelix is a hulking behemoth of a Steel- and Ground-type. On occasions where using raw strength is needed, relying on a Pokemon like Machamp (as Pokemon Sun and Moon did) is sensible. However, some of the larger Pokemon rarely get the chance to put their strength and size to use. Larger boulders still, or underground traversal mechanics, would require the unique size, power, and burrowing capability of the likes of Steelix. If this happened, it could open up new puzzles and dimensions to locations in the games.
2 Metagross
As a mighty pseudo-Legendary Pokemon from generation three, Metagross is as formidable in battle as it is popular. Using magnetism and telekinesis, Metagross is able to move its heavy body wherever it pleases. As a mount, Metagross could help players traverse vertically, climbing up walls and sheer cliffs. When Mega Evolved, Metagross even levitates. Gradually, more Pokemon are being physically employed in the way that the player traverses the world in the series, and Metagross would add another intriguing dimension to this. It could function similarly to the way Sneasler does in Pokemon Legends Arceus.
1 Rayquaza
There is so much more that could be done with Rayquaza. As the third Legendary Pokemon from the third generation games, Rayquaza is the ruler of the skies. The third generation remakes did two things that that would make it a fantastic mount. First, it allowed players to soar through the skies on Latias and Latios (along with their associated Mega Evolutions). Secondly, it added a Mega Evolution for Rayquaza too. It's a point in the game's story that only Mega Rayquaza can achieve the speed and height required to intercept an asteroid, as seen in the dramatic Delta Episode with Deoxys. This brief taste of a ridable Mega Rayquaza emphasized how exhilarating it could be to take command of the creature in space for a longer segment.