Hey there! Welcome to Smogon,
Divizoro! c:
I really hope you've been enjoying competitive Pokemon; it's so fun, and there's a lot to know, but as long as you enjoy it, anything is possible. It's great that you're learning the basics - that's the best way to start your journey into competitive battling. There are lots of roads to take after you learn and understand the basics. You can either go straight into battling, if you're more confident, or you can lurk around the forums, find a tier you enjoy playing (eg: Ubers (legendaries are allowed), LC (baby Pokemon) or Other Metagames (tiers with a twist!)), and hang out in the discussion thread for that tier.
And by looking at your profile, I'm guessing your favourite Pokemon is...
Magikarp Garchomp, right? My first game wasn't Platinum, but I did play it. I think it was a much better improvement to Diamond and Pearl, because on thing that really annoyed me in D + P was the the battle banners (screenshot below to explain what I mean) because they were so blurry! It didn't seem really fun, but I was glad that they made it better quality in the following games. My first game, in fact, was Pokemon Emerald / Platinum / Ruby. I had nothing better to do, so I played them all many, many times. Because I was such a terrible battler then, I used cheats to level up my Pokemon to Level 80 before the second gym, and I just swept through the entire game in like a few hours.
For advice on your team, you are most welcome to visit the
RMT Forums and submit your team there. However, make sure you read the rules before posting your RMT there. I'll just go through them very quickly to save you time from having to find the thread. You need to include 3-4 lines of description for each mon, post a completed team, and make it readable, so the raters can easily understand it.
If you ever need help with building a Pokemon team, you can check out the
Smogdex for standard sets which can help you a lot. You can also PM me if you have any questions, and I'm sure I'll be able to help you. You can also PM
deetah, and she'll be able to help you if I'm not online. Good Luck, and I hope you enjoy your times on the forum! n_n