Two questions

[Velmin]

Want to know: If traded Pokemon are weaker or has nothing to do with it?; and at what lvl is recommended to give Pokemon carbos, iron and others?

 

[pichufan25]

1. traded pokemon are of the same strength but they get more xp.
2. you can better start immediatley when you get the pokemon

 

[Master Mewtwo]

1st question. Pokemon do not get weaker when you trade them. The just grow by 1.5 experience points. Thast's the only difference. They keep everything, Evs, Ivs etc...

2nd question. I am not an expert at Ev training, but I do not think it matters what level you give them Vitamins. As long as you do it correctly then you can max them out at a very low level. I think I got that right.

Master Mewtwo

 

[ShinyManafi]

You start giving vitamins at any level, but you cna only give up to 100 EV points with them. The last 152, you'll have to do yourself.