One possibility is to take a mixed strategy approach. Companies facing this situation can buy into a pool, and then flip a weighted coin. If the coin comes up "fight" they get a team of heavy-hitting lawyers who will slug it out against the big corporations team of 100. This will ensure that at least some of the time, the bully will lose several million dollars. Thus, if the bully is given the odds, and motivated by their own bottom line, they may back down. You just need to turn the game theory against them.