Timeout after signing out
I love this site and have been reading its contents for months. I usually do not post, but I think I might have an idea how to make using multiple accounts harder.
How about if Niantic implemented a timeout, when someone signs out. The person will get a warning at sign-out that he will not be able to sign in again using the same account for one hour (as example). That could prevent the many users who use multiple accounts for cheating, since if they need to wait an hour to login back to their main account, since it might not be worth it for them. I think this will be very easy for Niantic to implement.
Answers
I can understand the frustration of Multiple accounts being used to take someone out of a Gym to put their own stronger mon in the Gym. However, I use the multiple account option to help my two kids with their accounts. If I find a particular mon they are looking for I log in to their account to get it. If I take the time on my lunch break to take down or prestige a gym, then I often will put one of their mons in since we are on the same team. I don't consider this cheating and it's not like I have the resources to keep more than 2 or 3 in a Gym at a time anyway. Time limits would damper my ability to help them out even if it would hamper cheaters. I still think there are way more important problems to deal with than multiple accounts.
In your situation that'd clearly put you in disadvantage. I don't consider that helping your kids is cheating.
On the other hand, Niantic really need to stop cheaters. Without new content and people abusing the only competitive part of the game many of us feel discouraged to keep playing.
Maybe one hour is excessive, but at least 15 min would make cheaters think it twice without harming "helpers" too much.
When people complain about people using multiple accounts, they are usually complaining about people using an alt-account of an enemy team to knock the lowest pokemon out of a level 10 gym, then switch to their main account to train back up 1000 prestige and put another pokemon into the gym.
You are right though that any action to address that problem would hurt a lot of legitimate players.
It's the same, both is cheating. In the game you're supposed to conquer the gym for your team, not to help your friends from opposing teams. (In the real world such people are called spies, in a war they're not protected by international law and are usually sentenced to death and shot when discovered)
