AgentJ, I think it may have been better if you focused by doing this on one series at a time, as you've done before. But considering that took 47 blogs to do already, yeah, I totally understand why you didn't. Though, I personally probably won't comment on every single one of these guys, but I'll give this a shot.

Mario: I think the super giant Mario from New Super Mario Bros would be preferred. It would also be cool if on old-school 2D levels this giant Mario was his original NES sprite like we see in Super Paper Mario. I think that would add a nice little amount of variety and awesomeness.
Luigi: I don't know about your suggestion on this one. While it could be cool seeing Luigi bouncing all over the place and kicking his legs the whole time like he does, I think I'd like to see something a little more creative. Maybe something involving his Luigi's Mansion vaccuum, but I'm not really too sure.
Peach: Haha, yeah, that one is perfect and a hilarious concept. I agree.
Bowser: I'm down with the return of Giga Bowser return. Since you mentioned his sons, I think it could also be cool if he called them out and for about 10 seconds the other brawlers had to try to defend themselves from all kinds of wild attacks from Bowser and his 9 or 10 kids.

Link: A full triforce, eh? Hm... I'm not opposed to the idea, but it is hard to think of what to do with it exactly. Maybe this is silly, but I'd be pretty amused if he played a song on his ocarina and it caused dozens of crazy enraged chickens to fly all over the level and attack the other opponents. Maybe that kind of attack would be best reserved for Young Link or Toon Link if they were their own separate characters, but I prefer your idea of them serving just as alt. costumes, so in that case it would need to work for for each version of Link. Oh, or how about the return of Firece Deity Link? He could put on that final mask from Majora's Mask and do a whole lot of damage.
Zelda: Yeah, light arrows are really awesome. These can stay.
Ganondorf: My problem with his final smash is that it was so short. I like the idea, though. I just think perhaps they should modify it a little bit.
Vaati: You have the right idea on this one.

Samus: There's a lot you can do with her. I was thinking her power bomb could also come into play, but I really like the idea of bringing in phazon powers. I know you played Metroid Prime 3, AgentJ, so what do you think about that whole phazon mode craziness coming into play here? I think that could be pretty darn beautiful.
Ridley: I totally don't know. I'm still not sold on Ridley as a playable character, so I'm not so sure where to take this one.

Fox: My problem with bringing Great Fox in is that I don't think it would seem very fitting for most of the levels, but I guess that's never stopped them in the past. I think perhaps it'd be cooler if Fox himself did the attack by maybe hopping into his arwing and doing 2-3 fly-bys.
Falco: Yeah, okay, I like this idea. Maybe my suggestion with Fox is too similar to it, so perhaps that's why you went with Great Fox. This is one I'd certainly like to see happen.
Wolf: I do agree that only one character should have the landmaster. I'm still not totally sure that I think it should be in the game, though. This has kind of got me thinking. Since I think Wolf should be an alt. costume of Fox, I think Fox should be the one that gets air support from Slippy, Peppy, Falco (if he's not in the fight, otherwise maybe they could use Bill or someone). This way, Wolf could have the same final smash, but instead his Star Wolf team would be the ones giving air support (Leon, Andrew, and whatever the pig's name was). With that idea, Falco would need a new Final Smash entirely since he doesn't seem appropriate for summoning Great Fox. I'm sure something could be done, though. I like the idea of incorporating bombs somehow, like the Arwings use.
Krystal: Hmm.. I don't know. We don't really know all that much about her. If done right, the ground slam idea could be cool, but maybe more could be done with her.

Captain Falcon: Yeah, I agree with you on this. The Brawl one or FALCON PUNCH-OUT!! Man, they should have made him the new final boss in the new Punch-Out!! How hilariously awesome would that have been? Okay, okay, maybe it would have been too cool. Okay... deep breaths. I'm calm.. I'm calm. Okay, we're good.

AgentJ, dude. This is too many characters, man. I'm gonna call it quits now. I'll try to come back to this later to comment on more. If you see that I haven't within the next couple days, you can just send me a message and remind me and I'll try to get back on it for you. Your blogs deserve more of a response. You've put so much effort into all of this and too often many people pay little or no attention to them.

Lol, its just something to pass time. I enjoy it, but i'd enjoy it more if people actually submitted their own ideas. Doesnt look like that's going to happen

Very active imagination, I have to say!  Especially towards one game.