>>37193543It's just in line with an old-timey fashion of names; for example, names in the Bible like "Jesus of Nazareth." In many cultures, villages/tribes acted as family, even if not everyone was blood; and thus, people simply went by a single name and then the place they're from served as further I.D. And because villages and tribes were tight knit, no two people in one generation had the same name, so confusion was never an issue.
It just so happens that certain non-trainer "professionals" like the professors are referred to only by their last names, with Bill and the other PC operators being exceptions.
>>37193916As
>>37193930 said, it depends how long they've been at it, as well as what they're catching them for. It also depends how many they're actively training. For example, Red's rival is clearly stated to have caught many dozens of Pokémon in a fairly short time, while Red has only canonically been shown with 7 (assuming his Espeon is just in the box); and, if I remember correctly, by the time Ash caught his 7th Pokémon Krabby, Gary had already caught 45 Pokémon (however, it's important to note that many of those were stated to be multiples of the same species, and were probably caught just to give to Oak for research, with no intention on ever training them).
So, is the trainer competing in the Pokémon League? If so, then they should have a team of 6, and maybe a few extras to alternate with. By this metric, a trainer who theoretically has traveled through Kanto, Johto, Hoenn, Sinnoh, Unova, Kalos, and Alola, could reasonably have over 40 trained Pokémon, assuming they pulled an Ash and started fresh every time.
