|you entered a battle with a ranger who has already done a few battles. This means, his opponets will be much stronger than the ones you would get by fighting alone. |
When doing RG, you need to remember that it works like a normal fight, except opponent is AI controlled (sometime you'll stumble on a real player, same configuration).
Also, your opponent gets stronger the more fights you win (like in TG).
So to beat it, you must use quite a lot of artifacts, and i would suggest you not to join RG fights unless you know the person that is asking for help. Without some coordination, there is no way a 2 vs 2 can be won in this situation.