Evolution Glitch (works every time):
1. Deposit the trade evolution Pokemon for an impossible Pokemon (I myself ask for a Lvl. 9 and under Abomasnow), with the necessary Trade Items if needed.
2. Do a trade, any trade, but STAY ON THE GTS.
3. Check on your Pokemon (in this case, the Kadabra), but DON'T TAKE IT BACK.
4. "Summary" should have changed to "Deposit Pokemon" (weird, i know).
5. Exit and re-enter the GTS.
6. Take back the Pokemon (in this case, the Kadabra).
7. Your Pokemon WILL evolve.
I have done this trick contless times; it's very useful.