Rock paper sissors and the use of cards

[MetaMetaGross]

a few weeks ago at my league I was testing a deck. I use Team Galatic's wager as sorta annoyance card and for fun to see how many times we have to do it before someone wins. I played one, the young kid I was playing with pulled a stack of 3 cards, picked one and said "ok go". I was shocked. I was disappointed. How "offically" is this kind of situation handled. Or should we all just get cards?

 

[PokePop]

It is officially acceptible for a player to use cards to choose.
You can still do it manually, or use cards yourself.

It doesn't affect how many times you might have to do it.
After all, you could still choose the same thing.

In fact, I was playing someone last week after a City Championship was over and we chose the same thing about 75% of the time. It was pretty funny.