What are the best natures for arcanine? I have an adamant one that I'm attached to but I hear jolly, impish, calm are good too. Are all of them good? Is adamant a good nature for him?
The best would be Jolly nature (+Spd, -SAtk). Arcanine (and Growlithe) can learn a lot of potent physical attack moves, some of which cover multiple types. If yours knows good special attack moves, go with Timid nature. (+Spd, -Atk)
Hope I helped!