There are new evolutions available only from a Pokemon trade or by Pokemon increasing a level while equipping an item:
If you trade a Magmar while holding the Magmarizer (held by a wild Magby) it will evolve.
If you trade an Electabuzz with the Thunderizer (held by a wild Elekid) it will evolve.
If you trade a Rhydon holding Protector it will evolve into Rhyperior.
if you trade Porygon 2 while holding the Dubious Disc it will evolve into Porygon 3.
If you trade a Dusclops while it holds a Reper cloth it will evolve.
If you level up Sneasle holding the Razor Claw at night it will evolve into Weavile.
If you level up a Gligar while holding the Razor Fang it will evolve into Gliscor.
Also there are four pokemon from the very original if you played it that evolve without hold items through trade (machoke=machamp, kadabra=alakazam, haunter=gengar, gravler=golem)