Ahhh... I've thought this too, but I'm not sure if there's an actual "rule" about this.
Is it not alright? As far as I know, it's totally okay to use a logical number of moves according to your story. Must you use the same as the games?? Hell no, I've given a Flareon Flare Blitz and an Espeon Aura Sphere because I can and it doesn't look silly.
As far as my knowledge goes, there's nothing wrong with a certain number of moves, as long as it doesn't look absurd or overpowered.
10th prestige Lv 55 Nightmare
I still Like wafflezzzz...