Is it also possible to describe minél with: mi mellett?
could it be "min vár a fiú, a vonaton vagy a villamoson?"
No. "Minél" means next to something, while "min" would mean on the vehicle itself. So if you say "villamoson" it means you're on the tram (and possibly travelling), while "villamosnál" means you're standing next to the tram.
By what is the boy waiting the trai or the tram. Is no good?
If you add the 'n' at the end of "train", it's good. :)
Doesn't "waiting by" need "mellett" and not "-nál" in the translation?