Saying "ff" and "reported" once won't get you banned. Bans don't happen for single instances of giving up, or mild harassment. Chat restrictions and suspensions happen for repeated instances of negative behavior. While you may have only been shown this one game as your Reform Card, that doesn't mean that it was the only game you were reported for. It's possible that you were reported for quite a few other games to push you to the punishment threshold which led to the 25 game chat restriction. As far as reporting other players and them getting a ban, it's the same thing. If they haven't been consistently negative, then no, they won't be punished based on your one report. It may take more games and more reports for them to reach the level that the system decides is worthy of punishment.
As far as saying "reported," there is honestly no reason to ever say it in game. It's a threat, the same as school children telling other school children "if you don't leave me alone, I'm going to tell the teacher on you," or coworkers telling peers "if you don't leave me alone, I'm telling your boss," or an inmate at a jail telling another inmate "back off or I'm going to the warden." If you consider each of those cases, you'll get an idea of what the "benefit" of using that threat on your teammate will be. In a school yard, you will end up the object of even more bullying by the people who are on your case; so your teammates will just harass you more for saying it. In the office, no one will ever want to work with you again; so your teammates are certainly not going to want to work together with you to win the match. And in a prison, you'll just get shanked; your teammates will watch you die and possibly even laugh as you do. (In these examples, I'm specifically referring to teammates who are being threatened with the reporting, not the neutral ones who aren't on a side, btw.)
The way the system works, it only takes one report to flag a game for review. Yours. So /mute them. And report them after the game. When you start hurling threats, and arguing, and laughing at them, insulting them, etc... you are no longer defending yourself. You are flaming back. And you are opening yourself up for punishment under the same system that would punish them.
Threats:
Kid Gir: reported
Kid Gir: reported
Kid Gir: report hec very toxic
Kid Gir: chat logs wont lie
Kid Gir: you called me scrub
Kid Gir: kk enjoy your ban
When you threaten to report someone this many times, and go out of your way to talk about the logs, and telling him to enjoy his ban, that's not defending any more. That's a threat. And yes, it's done in retaliation to them acting first, but it means you're not a victim anymore. You're a participant. And participants can be punished.
Complaining:
Kid Gir: still waiting for a gank :/
Kid Gir: took you 13 minutes to gank
Kid Gir: also when you ganked you did nothing but walk into lane
Kid Gir: zero ganks in laning phase from you vs zacs 2 and panth roam
This is another set of things that are actively complaining and arguing with your team. While it may be completely true that he didn't gank before 13 minutes, pointing it out repeatedly and complaining about a failed gank are not going to help your team win the game. Some junglers do not gank early. As a player, you have to be ready to adjust how you play the lane around that.
Kid Gir: im just lauhging at him lol
Kid Gir: yawn, at the end of the day idc how childish hec is
Kid Gir: im behind on my own accord now lol im laughing at you and renek
Kid Gir: this is too funny to play the game
Laughing at your team, insulting them, and admitting openly that you are not bothering to try and play or win the game can very easily get you reported. Especially saying things like being behind because you're too busy laughing at your team to play.