Who would you send? Why? And will he dominate all the fighters from that time?
I'll send Jones to Pride to fight a young Rampage, Arona, prime juiced out his mind Wand, maybe Vitor, young Shogun, and possibly Fedor or prime Cro Cop. LHW fought HW there. Maybe even a prime Liddell. Sounds interesting to me.
Also I'll send GSP to the first UFC tournaments and fight everyone and not just his weight class. 
" prime juiced out his mind Wand"
the personification of offensive brutality
TTT
Send current Hendo to past Hendo
Jcvd to ufc1 
Anderson or Cain to UFC 1
GSP to UFC 1. He would have had like a 100 fight win streak. And would have probably never even been punched or kicked by any of his opponents.
BigFoot Silva to Pride freak fights
Fat bj penn vs 2001 skinny bj penn at a catch weight of 163
10Marlons - I'd send Schaub to 2006 to get his whooping by Cro Cop.
Good call
Would Kimura in UFC 1.
Roy Nelson to UFC 1.
lavar johnson to the beginning of the ufc, UFC goat
Send Brock to UFC 1. :).
send Jon Jones back to the pride GP shogun won, and see how he does. Maybe have him replace the dude wand fought in the first round.
Ubereem to fight 205 overeem
Rickson to be Mark Coleman's first UFC opponent.
JDS vs Fedor in his prime.
What if, indeed.
Today's Anderson Silva to 2007 to fight Fedor and settle the GOAT debate.
I'd like to see brock fight at UFC 1.
Not because I think he'd win, but because I'd like to have seen him 2-3 or even 4 years afterwards. I think with his freakish strength and wrestling abilities and no diverrta...however you spell it. He would have been a frwaking monster
Imagine prime Mike Tyson to one of the first couple UFC tournaments
DCiocia08 - Send gsp back to pride.. Knees to head while down would work perfect with his ability to hold guys downI've thought this for a while.
GSP knees in the ground = raep raep.