So i ran into a trainer on the battle thing and he had a greninja and it changed forms or something like that and it interested me so i was wondering what i have to do to get it or how to do it help would be appreciate

That is what Protean does in this game to denote what type the Pokemon currently is

ohh ok so how would i go upon getting one because i dont think that all Greninjas would have that ability

It is the hidden ability. I don’t think froakie is available in friend safari, so you gotta use dream mist at gaea town ( a guy in a house does it) to change a normal greninja’s ability into it’s hidden ability.

You can get Pokemon with hidden abilities on friend safari. It’s a low chance, but it’s made for that.

idk if i am a noob for this but i dont get the friend sarari

it’s in the friend safari. you gotta enter the cave entrance up stairs and connect to the internet. Then go to the wiki and seach for a water type friend safari and then search for frogadier. Visit his base and search around for a frogadier who has protean