We just don't know when
Any enters abilities of the copied creature will trigger when the token enters the battlefield
For example, if you cast a spell that deals 4 damage divided among any number of targets and you choose to have it deal 2 damage to a creature and 2 damage to that creature's controller, that spell will deal 4 damage to each of them instead
Monster Tokens may be used as Tribute or material for Special Summoning methods (except Xyz Summon, as Xyz Materials are not treated as being on the field), but cannot be used to pay any cost that involve a monster moving to a specific location (they can be banished, as the banishment is not considered a location, but will still disappear permanently since they are leaving the field)
Pokmon is more like the anime and video games when it comes to attacks in the card game
Instead, Im trying to think though what we should mean in vintage circles when we call something rare. At the least, I think it is useful to circle the wagons around some potentially unethical uses of the term