How do you train your pokemon?
Also,When someone is looking for a trainer how does that work?
When you lend someone a pokemon can they level it for you?
Otherwise....Idk :) thx for the help

You go to NPC fights and battle npc trainers, but to train fast you can try and get Toxic and get some Golurk/Golett and battle Zapmolcuno or Mysterious Stranger which you need all badges first. You can use the "Search player" option and type their username, and yes you can loan someone a level 5 and they can train it to 1000 without worrying about the level cap. :)

When i first started i went after all the gyms. Then i heard about the Mysterious Trainer and thats what i do now.

You go to NPC and battle the swimmer. Make sure you have an electric move learned by your poke.
You need gym badges if you want to battle the mysterious trainer that boon5667 and phoenix1337 mentioned but I recommend not to battle that unless if you have toxic and much better if your poke has fly.

I have started training at the Mysterious trainer

you face the swimmer(intermediate npc trainers) when you first start out. i am currently training against the mysterious trainer.

I am battling Mystery Trainer but if it doesn't know Toxic Then go to NPC fight and Battle Swimmer Richard and use Bolt Strike 2 time then you won't level up every time but you will every once in a while.

i am training in the NPC fights,i am battling zapmolcuno or the bird tamer,i am training up to level 500 for free but all trainers that wanting me to train their pokemon must change their pokemon's attacks,blizzard,bolt strike,blue flare and megahorn,that are the attacks that the pokemon must learn before i train their pokemons,i am also lending my level 4052 for coins or shiny pokemons,hehehe,that's all

Read through this,it will give you all the help you need - [you must login to view links]