Canadian and American Rating System
C: Programming suitable for children ages of two to seven years. No profanity or sexual content of any level allowed. Contains little to no violence.
C8: Suitable for children ages eight and older. Low level violence and fantasy horror is allowed. No foul language is allows, but occasional "socially offensive and discriminatory" language is allowed if in the context of the story. No sexual content of any level allowed.
G: Suitable for general audiences. Similar to the Canadian/American film rating of the same name; programming suitable for the entire family with mild violence, and mild profanity and/or bleeped language. No sexual content of any level allowed.
PG: Parental guidance. Again, similar to the movie rating of the same name. Moderate violence and moderate profanity is allowed, as is brief nudity and sexual references if important to the context of the story.
14+: Programming unsuitable for viewers aged younger than 14 years. May contain strong violence and strong profanity, and depictions of sexual activity as long as they are within the context of a story.
18+: Programming intended for viewers ages 18 and older. May contain explicit violence and sexual activity. Programming with this rating
Source Wikipedia
As you see, C8 is the second lowest Rating, and C being the lowest rating,
Pokemon do tend to nail each other ( Tackle, Pound, Etc. ) Shoot Fire from their mouths ( Flamethrower, Fire blast, Ember ) And moves that involve Lashings... ( Vine Whip, Power Whip )
So naturally, there is very very low level violence, but high enough to rank at C8.