So I played it today at a friend's place.
Well, in my honest opinion, and I'm no snob about SSBM, the items, especially the smash ball, break the game.
Whenever one appears it becomes 'everyone chase the smash ball melee!' and once somebody gets it then it's quite frequently an instant knockout for all other players.
Maybe I'm exaggerating a little bit, but that's my experience after a couple hours with the game.
Helper trophies and pokemon, while intersting visual candy, only served to further absurd-ify any balance or technique that was present. Again, once a helper trophy appears, it's a mad rush to get that, and pokemon are, well, hit or miss, however there are a lot more insane buster pokemon now.
The most fun I had was when there was no smash ball and I was duking it out with any other character, trading blows and maneuvering into advantageous positions.
The least fun was any time anybody got a smash ball. Even when it was me, because there's no skill involved after the ball is got. Just hit the win button. (B)
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Second-take
It may be the settings that we used that caused my game experience to be so poor. If the smash ball is less frequent than I encountered, then perhaps its occasional 'win button' is forgiveable.