Question

So, say I have a Magmar and Electabuzz in my Pokemon Platinum and they have a magmarizer and electrilizer and I migrate them to my White 2 game, will they evolve?

Comments

I don't think so..

Answer 1

No. They will not evolve. They will only evolve if they are officially traded. Trading between generations using Pal Park and poke transfer do not work.
Also another thing, Pokemon from poketransfer cannot hold items so either way it wouldnt work.
Source: experience. I transfered my graveler a while ago to see if it would evolve and it didnt.

Answer 2

No, they won't.
Migrating doesn't work the same as trading.
Sources: Experience