If you release a movie online it just gets leaked in under 2 hours.
If you release a movie in theatres you have no way to distribute the skin/pack.

Yes you do. You can definitely distribute the skin/pack in theaters. Yu-gi-oh actually did release some card at one of their movies. Tons of people went to see it just to get the card.

They would just give away a card with a code for 1 skin/pack. Like they do at pax.

I guess I'm thinking more of high budget movies. A movie like this would be at events and lower budget.

That just isn't true though. Why would it be low budget? Riot grossed over a billion dollars last year. A movie about the most popular game on earth probably would make money. LOL

I still remember getting my Mew and Dragonite cards at Pokemon the first movie (which topped the box office btw)

I don't know... Would definitely be a first.

They should sell FaceHunter Starter packs

Someone never went to see Pokemon in theatres to get an Ancient Mew card.