He doesn't have to use those move types against the x or y legendary.

You are also forgetting his ABILITY.

His ability reverses the effects of the X and Y's ability.  Which is "This ability will increase the Power of all Fairy-type moves in battle" and "this ability will increase the power of all dark-type moves in battle"

So his ability will make all fairy and dark moves WEAKER in battle.  So while he can't use his type movies Ground/Dragon, the others can't use their type moves cause they will be super weakened by his ability coutnering their ability.

Complete list so far. Changes are Skerlp evo is poison/dragon!!!

Assuming the second eevelution rumor is false.. ):

I wanted a poison eevee. :( 

Yeah, but odds are that it will increase it's dmg by 1.5 just like drought does which would be fair but drought is a increase of all fire move (and decrease of water ones) while Blastoise's ability is only valid for water pulse so it's still unfair.

And water pulse has attack power of 60. So it would put it at 90power, still a weaker nuke than Hydro Pump's 120. So it would increase the dmg of a move that will probably not even be our main weapon. If howerever it doubles the dmg instead of doing 1.5x (which would be fair but I doubt will be the case since game freak seems to be stubborn into keeping fucking over every starter that is not fire), it would equal the dmg of Hydro Pump. In that case It would still not be phenomenal but I'll admit would be still pretty good since it will become a hydro pump with the advantage of more accurcy/PP and a chance to confuse.

I hope it doubles, if not I hope it's like Zero says and increase the dmg of Hydro Pump aswell since it's Blastoise signature move and a pump move is kinda the same as a pulse move in my logic. If either than Blastoise gets screwed.

He can activate Rain Dance as well as his water pulse ability

So he will get a lot more damage that way.  But are you just trying to say pulse is weaker than hydro pump?  So what.  That's same as the argumetn of Thunder vs. thunderbolt.  Thunderbolt is prefered because it has 100% accuracy while thunderbolt is like 70-80.  Hydropump is 80% accuracy, while pulse moves are 100%

If this ability puts Pulse near or at hydropumps power then it wins on sole fact of 100% accuracy.

Anyone disappointing in Goodra's type?
Was hoping for Poi/Dragon or Fairy/Dragon, but Dragalga reedemed that type, but Goodra was begging for that type ):

I'm pretty happy it stayed pure Dragon type, sense very few pokemon remain purly dragon. 

Im more disapointed in its stats, its looking like a sp def wall which is not what I was hoping for.

To be fair, most dragon types (pure or not) are already ridicolous in power, so it's a nice change that we got a Dragon Wall.

Goodra does at least redeem the Pure Dragons as the crayon drawing Druddigon pretty much put a black mark on them.

Edit: Hello 21st century, I'm now at 2000!

im happpy, we get a wall, and a pure puesdo! Dragon pure types are rare, last gen had the first two fully evolved. This gen we get one more! I wish we get some pure Flying type as well so it can resist fighting instead of nor/flying