>Game forces you to use a legendary pokemon against the final boss which denies you the chance of having a hard battle
This is the definition of soulless. An actual good game would have commended the player for going out of their way to make their playthrough more challenging by giving them an achievement or making the other characters have different dialogue where they acknowledge the player's choice, but here the devs automatically assume you're too retarded to win a fight against someone with a legendary pokemon unless you yourself have a legendary on your team.