Because apparently people see a pattern that hasn't even came up yet.
so why do people think that PT will be replaced by different gen PT
It's not about "seeing a pattern" actually following patterns is a misleading train of thought. It is futile. I can't remember the name of the dilemma but it goes like this:
"Just because X event happened every time until now, doesn't guarantee it will happen again in the future."
An example would be, say you go to the park every day, and every time you go there you see an old man feeding pigeons. Every day you go, every day he's there. Now, can you guarantee that he will be there next time? Well no you can't ( he might die, get sick, have a change of plans, etc...). You can be really sure he will be, but there is no certainty. Your mind notices the pattern and expects it to happen in the future, but in reality, the events are independent from one an other. The past and future are NOT interdependent. Well, at least not to that extent. So just because something was true in the past doesn't mean it's guaranteed to be true in the future as well.
Now that's what people need to realize when looking at the roster. The previous patterns we've seen before serve as decent starting points, but they are by NO means set in stone. You're better off using critical thinking, and analyzing why certain characters could fit in the game given other criteria. Think outside the box.
So, in the case of Pokemon Trainer it's the following:
We have 4 Pokemon characters (I'm counting PT as one for simplicity's sake).
-Pika
-Jiggs
-Lucario
-PT Red
Mewtwo was supposed to be in according to Rumors.
Now, we can be sure another Pokemon rep will join in one way or another. Why? Because this roster is now outdated as far as representation goes. Now lets keep in mind one thing. Generation 5 is BIG. It is an important Generation as it's the REBOOT of the Pokemon series. The intent of Black and White was to go back to the roots and try to work things up from a new point, making the games bigger and more story focused, a very welcomed change among the Pokemon Community. To further support this point, B/W are the first games to get direct sequels with B2/W2, something we've never really seen happen in Pokemon before.
So with that mentioned, Gen 5 is indeed worthy of a candidate. Now, as a reboot, it's very likely that Gen 5 will replace the original PT, why? 2 reasons. 1, The Unova Trainer/N is like the NEW Generation, even more so than the previous trainers. It's not new as in the NEXT generation, but new as in a whole different take on the franchise. Putting Hilber/Hilda/N in, is not the same as putting Dawn/Lucas in. They are more Iconic trainers as a whole simply because Gen 5 was the reboot of the series.
Then the argument comes up. "Why don't they put Zoroark in and keep Red?" There's that nasty pattern thinking again. See how it trips people up. Not saying it's impossible, just saying its a poor uninspiring choice. When you follow patterns in game design, games become predictable and boring. You gotta be vibrant and innovative down to the simplest details. I see what you're trying to say: Have Zoroark replace Lucario and keep the rest of the cast, add Mewtwo. But see, that pattern doesn't quite work... For one, Mewtwo was supposed to be in Brawl to begin with, but was cut for whatever reason. Meaning, Lucario was never meant to replace him, thus rendering your pattern invalid. Second, as I said before Zoroark isn't as Iconic to the Pokemon Franchise this Generation as Lucario was to the last, the focus this time around falls more on the trainers, thus, making a new trainer a wiser choice. Lastly, Generation 6 is just around the corner, and will surely be (at least) announced by the time SSB4 comes out, meaning, we're likely to have a new candidate to take Zoroark's "iconic role" before then.
So, with all that in mind, lets looks at what we can do:
In my opinion, Having Red get replaced by a Unova trainer, be it: Hilber/Hilda/Rosa/Nate, or N, would be a good iconic representation of what happened to the Pokemon franchise when Gen 5 rolled along. Not to mention, this brings the opportunity of being able to have Red as an in-game-Boss where you are challenged by him a la Mt. Silver in Gen 2, thus paying homage to that classic scene.
Pika and Jiggs stay because they are Iconic due to the anime.
Mewtwo makes his desired comeback due to fan requests and the fact that he was supposed to be in anyway. Also, he serves as a good rep of the Classic days of Pokemon.
Lastly Lucario is a give or take, he's up in the air, either he stays, or maybe he gets replaced by someone from Gen 6. His situation is actually the hardest to predict to me.
Just my two cents is all.
Thoughts?
Oh and...
>inb4 tl;dr