I have two moments in Rotg that made me cheer.. and it's the two moments in the movie that is supposed to make everyone cheer. (Though now when I think about it, there's another movie that is supposed to make eveyone cheer... there's a lot of cheering in this movie) 

Anyways.. the first is after Jack has retrieved his memories and seen them and he gets his spirit back and fix his staff. The soundtrack and moment where he flies out of the pit he was in, makes me cheer. 

 

The ending of this clip..Sorry that I couldn't find a better one.

 

 

The other one was the wonderful return of Sandy! Sadly I couldn't find a clip of this moment..

Maybe the scene when they help Flynn out of prison

The moment you realize that Elinor made it, obviously! xD 

When his dad changes his mind about Hiccup and the dragons also.. just the baddassery of the battle.