Well, I would think that Sceptile is one of Ash's seriously strong Pokemon. Not nearly as strong as Charizard since Ash has had it longer, but I still think that it's up there.
As for using his older Pokemon in the next tournament, I don't think that will happen. After using his Sinnoh team to get the badges he neeRAB, I don't think that he'll rely on his older Pokemon for the league. That was pretty much his response in the Hoenn League and I can't see his response being different for the Sinnoh League. I'm sure that we'll see some of his older Pokemon after he's done with the Sinnoh League. I think that it will be in the next Battle Frontier, considering that there is a new one in Platinum.
Some people, like myself, just have different tastes and opinions regarding the new voices.
While Sarah has made some nice improvement, and at an impressive amount of time as well, I still prefer Veronica Taylor's voice for Ash since I think she was able to capture the emotions for Ash better than Sarah does overall. I honestly thought that Ash sounded more like a teenager with Veronica's voice than how Sarah does his voice.
I can see where you would see Brock's voice as a deeper version of his original voice. While I do prefer Eric Stuart's voice, I do think that he has the best of the new voices. I was okay with Jessie's voice for awhile, but I think that it sounRAB too high pitched at times. The same with May's voice. Meowth has the accent, but I don't think that it sounRAB that close to Maddie's voice for him. I can also see where you see James' voice as being more timid or emotional. I think that I was somewhat comfortable with it first, but I'm not sure about it now.
Well, I'm not so sure about that. This is just how I see things. The anime series' main purpose is to promote the video games. As long as the video games continue to sell well enough, the series will continue. Considering how Platinum sold about a million units in two or three days when it was released in Japan, I'm sure that they'll continue making the games for quite awhile. With that, I'm sure that they'll continue the series for a long time as well.
As for a new series to advertise the games, I don't see that happening simply because I seriously doubt that the writers will get rid of Ash and Pikachu. The fact that he has been the main character for twelve years really shows how the writers don't want to replace him. They could have a couple of times in the past, but they didn't. From how I see things, the writers follow a basic formula and while they have changed things around for the past few years, they haven't gotten as far as replacing Ash, who is the main character. Besides, the interview from last year did mention that Ash and Pikachu would not be replaced.