That depends on what you need and what your region is like, anonymous. Different terrain and different forms of transportation call for entirely different pokémon. For example, for an island region, it may be more important for you to have a pokémon that can Surf or Fly, at which point many of the ones that can learn either move are suitable, even if they may seem small. (You’ll be surprised at how much a farfetch’d can carry … or how it does so, for that matter … or how quickly.) By contrast, a mountainous region may require a pokémon well-suited for navigating rocky terrain (such as rhyhorn), one with high endurance (mamoswine), or one adept at climbing (machamp)—or alternatively, one that can fly at high altitudes (dragonite). For long distances across even, dirt fields, you may find it suitable enough to use any number of traditional riding pokémon, such as tauros, rapidash, mudsdale, arcanine, or dodrio, but if you were planning on getting through long distances over water, you may wish to have high-powered water-types, such as lapras or gyarados.

In short, it entirely depends on your needs, anonymous, but you can generally figure out what would be best by looking at a pokémon’s physical capabilities. If a pokémon is known for being able to endure certain types of terrain or if they’re known for certain types of qualities (such as speed or even their docile natures), chances are they’ll make excellent riding pokémon.

In my experience, quite well.

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Edit: I have just been informed by my editor that I’m only allowed to make that joke once on this blog before “it stops being funny,” and therefore, I’m to offer an actual response to this question.

The truth of the matter is no one’s quite sure. The going theory is that those who use Metronome tap into some ancient gene (passed down from Mew, supposedly) that allows a pokémon to use any move in existence. This theory hinges on the idea that most elements and techniques are actually hard-coded into a pokémon’s DNA; it’s just that pokémon can’t use just any move in existence due to the physical limitations they’ve gained through adaptation and the slow, progressive sort of evolution. However, Metronome allows a pokémon to override these blocks and call upon elements and techniques just once, at random.

The other theory, which is slightly less popular (although it makes somewhat more sense to me, personally), is that the pokémon doesn’t call upon a random technique but rather the move itself does. That is, the user merely conjures an untamed sort of energy that manifests into a random move, occasionally even puppeteering its own user in order to do so. This explains why a pokémon is often incapable of remembering how to use whatever came out of Metronome until they attempt the Metronome technique again (and sometimes not even then).

Not necessarily, but yes, you won’t be able to enter any league battles unless you select six to carry with you, and if you have a trainer’s license (this also applies to those registered as any of a number of trainer off-shoots, such as coordinators), there are League-enforced rules and regulations on team limits you’ll be forced to follow. Of course, if you have a trainer’s license, you’ll also have a storage system account, so the six-pokémon limit will be enforced automatically anyway.

That aside, though, even outside of League rules, it’s actually highly discouraged to carry a large number of pokémon at once. This is because the more you carry, the more difficult it is to give a pokémon the care they need. Additionally, there are certain environmental laws in place that limit the amount of impact a trainer may have on a location. For example, some parts of Alola are protected areas, which means that while trainers are welcome there, there are strict rules in place that basically state that they must leave the area (jungle, national park, wilds, and so forth) as they found it. Or in other words, you wouldn’t be able to release all your pokémon at once to feed them, as this would be considered a disruption to the natural landscape. 

However, if you weren’t traveling and if you had a home of your own, this would of course be a non-issue, and so long as you can take care of all your pokémon in a humane way, there are no laws restricting the number you can have. Note of caution, however: There have been many cases of pokémon hoarders, particularly those who treat their pokémon as objects, neglect them, or raise them in fantastically unhealthy living conditions. In these cases, yes, it’s possible to have pokémon be taken away from you, but we’re assuming you’re capable of taking care of your pokémon in a humane manner here.

In short, not necessarily in legal trouble, no (although you may be in trouble for related reasons in the case of environmental and pokémon welfare laws), but all in all, it would be safer to leave your pokémon at home, to stay home with your pokémon, or to store them in the system.

All moves are categorized not by the offensive effects they have on other pokémon but rather on the element they apparently are aligned with. All moves, regardless of whether or not they do damage, resonate with a certain elemental energy that can be either observed outright or measured through any of an array of sensitive lab equipment, such as the elementometer (a device geared specifically towards sampling and breaking down a move’s resonant energies into types). A researcher just needs to get close enough to the move in use to take samples or record data, and the rest is fairly standard procedure from there.