Why does some pokemon like Beedrill and Marowak have bad moves of their own typing?

Why is this pokemon game so different to other fan made pokemon games when it comes to learning moves?

Why does electric type moves do damage to ground type pokemon, this is the first game and only pokemon game I have played where that happens.

this game should have a shop where you can buy moves for in game money like 5k plus to 12k per move.