1. Standby/Throwdown matches count as 'ranked', so go for
Sharp Blade, Sharper Skills first by entering training; pressing start
; RB twice
; and turning on standby.
2. To win matches legit, come prepared with ways to mix things up. If your opponent regularly blocks, you need to be able to throw or low attack. If they're spamming you with quick attacks, have one of your own prepared to retaliate (like Nightmare's punch).
3. If you're boosting and having trouble finding your partner, try both setting your regions somewhere with fewer games or where it's early in the morning. Then search for your region only.
4. After each match, you get the option to ask for a rematch. In general, until you have this achievement you should say 'yes' against any opponent where you're competitive.
Overall: five wins is a very reasonable number, and will hopefully act as a gateway drug to get you hooked on online and playing more! Start with throwdowns, try it legit, and rematch when you get the chance. Enjoy :)