Not quite correct. I don't know about you, but quite a lot of people wanted Charizard, and quite a lot of people pre-Brawl predicted that varying different Pokemon Trainers would, or rather should, be playable - and were normally greeted by being laughed out of town by people who thought they knew better about what kind of characters would be in Smash. When you consider that Red/Satoshi ranked quite highly on polls, it's not so unbelievable. The only surprise of the Pokemon Trainer, as far as I'm concerned, was the mechanic through which he was implemented - quite a few people predicted a trainer (although others called those people stupid), and in retrospect having the main protagonist of the series seems obvious now, but the thing that was truly surprising was the switch-out mechanic, which I don't think anybody could have seen coming.
That being said, a lot of people who suggested Pokemon Trainers got passed off as crackpot conspiracists because they were suggesting that anime characters be playable, such as Ash, rather than the more obvious Red. Either way, Pokemon Trainer was not as out-of-the-blue as people like to suggest.