I didn't really like the non-Mario characters either. Leave Charlie for some other guy...
As for Luigi not having a chance to beat Mario, that's true for the most part except for a few things. Shorter drives mean more control over where you hit the ball. Shorter drives mean less of an effect on draws and fades. And if the person playing Mario isn't able to control the ball well or anything, then that's your advantage.
(more unrelated Mario Golf stuff below)
Just like with Mario Golf for GBC, it says that you're best off with an average drive, control, and Straight shot. If you want to get the ball into the hole, work on getting your control stat up. If you just care about driving the ball as far as it will go, bring up your drive. And if you don't want your ball flying 50 miles away when you hit the ball, fix your draw or fade (also known as hook or slice i guess).
I made the mistake of not going for control when making my character for Mario Golf GBC. I got a 272y drive (thanks to that long drive club), but control was terrible and my draw was almost diagonal, it being so bad.
Anyway, whenever I'm not using Mario or Metal Mario (That's right, I don't use Bowser much), my favorite character is Yoshi. A straight drive, fair amount of distance, and good control. Maple has a straight drive and can hit the ball further, but I don't choose her because I don't like the way she looks (or dances around for that matter).