Are there any pokedex rewards for a certain amount of pokemon caught in game? If dont is there a possibility to be in game on the next history update?
When you catch them all you’ll be able to get a shiny charm.
That’s impossible right now since there’s only 1 obtainable legendary i suppose?
Of course, you’ll be able to catch them all next update though.
Thanks a Lot 
what about in randomizer i caught almost all legends
What is a shiny charm?
Sorry im kind of noob 
How many are currently available? Somewhere I heard it was 708, is this correct?
It’s 712 iirc.
Edit: Since there have been no new pokemon in 1.1.8. Edit2: Included delta wooper line, Halloween 2016 mystery gift.
And how many Pokemon are in the whole Dex?
Well, no one will be able to answer (or willing to, in case of those with the knowledge) that until 1.2 is released because of the deltas that are being added in the last update. That includes unrevealed ones 
Edit: In case any one is wondering, yes, all the original 721 pokemon will be catch-able in 1.2.
Will every Pokemon that was accepted into the Holon Dex be added in game?
No, not all of them are going to be added in game. Those that have been revealed to be in 1.2 have a 
nearby, like delta maractus etc.
Ok, that makes sense. Thanks for all the info