Since I was 8, when I started playing Pokemon, there have seemingly been certain principles regarding the EXP gain of Pokemon with certain typing. According to Oak in the first games, all Grass and Water Pokemon gain EXP much faster than Fire, which is to say that the EXP required to gain one level is significantly less for a Grass type than a Fire type. I now question the verity of this principle. For example: Sceptile gains EXP faster than Blaziken. Why? Apparently, this is because Fire types grow slower than Grass types, in exchange for being powerhouses. In addition, the secondary Fighting typing of Blaziken causes Blaziken to a have a slight increase in EXP level duration. Above all, it is pain for me to train Dragon Pokemon. Dragons, for some reason, have exceedingly high EXP counts for one level. All the types introduced in later games are slower to level up, with the exception of Dark. My question: What types level up faster, and why?