>>57892229
As for trainers with multiple pokemon it isn't very common. There is diminishing returns on investing in more than one pokemon unless you're really committed. While technically more pokemon will allow one to battle longer if need be, most people aren't travelling long distances in small groups to have need of such thing.

And in bigger brawls it can become a liability to have multiple pokemon that you would split your attention between. If you're giving an order to your magneton and your dugtrio decides it needs to use earthquake in the middle of a battle while you're fighting alongside the rest your knight squadron then you'll likely end up in a worse situation than if you had just called out your magneton.

For this reason trainers with two pokemon can be considered to be ace trainer level. To have more than one pokemon out at a time means that they are trained well enough that you trust them to battle alongside allies with minimal instruction. A pirate captain that trusts his Hitmonchan to board an enemy ship and battle without orders while he rides his Seadra to perform hit and run surf+cutlass attacks across the deck is a force to be reckoned with.

For these reason it is said to be the mark of a legendary trainer to command a team of six pokemon. So far only one such trainer has shown up in the story so far.

Whew. Ramble over.