Level isn't really whats important for competitive battling. The nintendo WiFi automatically levels pokemon to 50 or 100 (you designate beforehand). Besides, anyone can go and get an action replay/etc. to create or level up via rare candies the pokemon of their choice.
What is important, are natures, effort points, and individual values. All things relevant to your pokemon's stats. Natures give a +10% to one stat, and a -10% to another (for example, Jolly nature is +10%Speed, and -10%Special Attack). Effort points and idividual values take more time to explain, but send me a PM and I would be happy to if you like.
Also, most people aren't interested in legendary pokemon. Pokemon that are created by a cheating device or etc. are also not acceptable for trading. Since you want an Arceus, I will assume that you are obtaining things naturally though. Most people have way more pokemon (for example, I have 300+ competitive things).
Again, you don't seem to understand copetitive battling very well. Feel free to send me a PM for further explaination then above.