As you can imagine, when your child is being bullied, there is not one singular solution for all situations.
That said, you can tailor your child's solution more effectively if you know the bully type your child's tormenter happens to be.
As with every type of bully and bullying situation, the more insulated your child is with friends around or key people to go to, the easier it is to stop bullies. Similarly, stopping bullying early and comprehensively is critical, sot that it does not go viral.
There are 4 general types of bullies:
First, there is the Experimenter. The Experimenter is new to bullying and is "trying it on for size" to determine if bullying might help them climb the social ladder. In this situation, the first line of defense should always be to reason with the bully. Taking the the new bully off to the side and saying something like "hey that was not cool or it really bothered me -please don't," often assuages the situation. As always, if it persists, tell an adult. Stop it early and comprehensively.
The second type, the Old-Fasioned Bully is typically quite seasoned by 5th grade and started in second grade as a means to "fit in". The best way to address this bully is come back with a clear, but not completely threatening retort, , e.g., "Wow, who slapped you across the face when you woke up this morning, you are really not cool today." On the second occasion, tell the bully "You are really boring me (yawn with emphasis) and walk away." If it happens again, tell an adult. Stop it early and comprehensively.
The third type, the Elite Bully, is the most strategic bully and is probably poses the largest threat to a child's reputation. Elite Bullies can be the most popular child and ostensibly appear to be polite, get along well with others and genuinely liked by adults. Sadly, they are the most conniving. Elite bullies are capable of networking, recruiting and developing bully plans to execute on their victims. If this is your bully, it is trickier, because they usually have a large fan base and are extremely good actors ( and well-practiced liars). In this situation, it is ideal for another bystander or friend of a friend, to tell the Elite Bully to knock it off. Finding an older and more popular child to talk to the Elite Bully is something that should be done immediately. Further, letting the bully know you are not a pushover is critical. Looking him in the eye in a steely way is a good start. If the bullying persists, getting an adult involved early, before the Elite Bully starts to recruit or spread gossip (online, offline or both) is critical. Again, stop it early and comprehensively.
The fourth type, the Victim-turned-Bully, the most fragile emotionally and perhaps more erratic.Sadly, these children lack real friendships and only bully to fit in. Therefore, taking them off to the side and asking to make "a pact" ( "I will lay off you, if you lay off me") can be effective. However, if it persists, tell an adult. Stop it early and comprehensively.