That's a different case, where the moves are based on their actions, as well as the contents of their games. In addition, I said the use of her animal helpers could be used too, who wouldn't need moves made up for them. The only way this type of borrowing from the series would really work for Toad though is if his moveset was based around the sports games, though that seems like something that would be done for Waluigi (Who for the record has less of a chance than Toad) Additionally, I must restate that I'm not saying that Toad can't get in, but rather that his chances aren't nearly as high as you state they are. Heck, Mona's chances are iffy at best..
Toad can use moves he used in SMB2 and Mario Kart series and borrow moves from the generic Toads in NSMBWii. It is not any different from Ness borrowing Paula's PK specials, Zelda borrowing Link's magic spells from OOT, or even Meta Knight borrowing Kirby's tornado ability and Kirby's up/down throws. And you have to admit that Toad is far, far, far more likely to get in before Mona and even Waluigi.
So he'd use a item, a move that's been done to death already (egg roll, withdraw, Wario Bike, Rollout. Take you pick) Peach's move, and one pottentially creative move that would still probably end up like Snake's' up special. .
You just proved that characters can have similar moves. You just come off sounding like it is not okay for Toad to have some similar moves.
Bowser's Fire Breath, Charizard's Flamethrower
Bowser's Whirling Fortress, Donkey Kong's Spinning Kong, Link's Spin Attack, Samus's Screw Attack, Toon Link's Spin Attack
Bowser's Bowser Bomb, Kirby's Stone, Yoshi's Yoshi Bomb
Diddy Kong's Peanut Popgun, Link's Hero's Bow, Pit's Palutena's Arrow, Zero Suit Samus's Paralyzer, Toon Link's Hero's Bow
Ike's Quick Draw, Jigglypuff's Rollout, Luigi's Green Missile, Pikachu's Skull Bash, Squirtle's Withdraw, Sonic's Spin Dash, Wario's Wario Bike, Yoshi's Egg Roll
Ike's Aether, Kirby's Final Cutter
Ike's Counter, Lucario's Double Team, Marth's Counter
King Dedede's Inhale, Kirby's Inhale
King Dedede's Waddle Dee Throw, Olimar's Pikmin Throw
Lucario's Aura Sphere, Samus's Charge Shot
Mario's Cape, Peach's Toad, Pit's Angel Ring, Pit's Mirror Shield, R.O.B.'s Arm Rotor, Zelda's Nayru's Love
Mario's F.L.U.D.D., Squirtle's Water Gun
Mr. Game & Watch's Fire, Peach's Parasol
Olimar's Pikmin Chain, Ivysaur's Vine Whip, Zero Suit Samus's Plasma Wire
Pokemon Trainer's Pokemon Change, Zelda/Sheik's Transform
Charizard's Fly, Wario's Corkscrew
Samus's Missile, Ivysaur's Razor Leaf
Zero Suit Samus's Plasma Whip, Sheik's Chain
And not as a part of the debate whether Toad would get in or not, but wouldn't a small, fast, and super strong character not be a good idea?.
He would be very light and is not a good jumper to balance that out.
How are Toads more important? Toad was only put into SMB2 as a filler character to take up Papa's space, and since then never was playable in the main games, though it seems two different colored Toads will show up in NSMBWii (Why they didn't just have the normal Toad, and use the 4th slot on Wario or Peach is beyond me) Yoshi wasn't really playable either, seeing as he was just a mount. (Though that did change when he got his own series, which he's represented under) Koopas, Shy Guys, and Goombas (Who I'm not really going to advocate due to the fact that they simply have no arms, but when you mention the other two, you kind of have to include them) are the main flunkies you see in like 90% of Mario games, and are actually active in said games, instead of sitting on the side giving information. Still I guess I shouldn't really comment on this whole thing until more info is given on NSMBWii, since that could be a turning point for Toad, depending on his technical role in it, in relation to the two playable Toads within the game.
Toads are very important to the whole Mario franchise. They help Mario out in many games and they were major NPCs in Super Mario 64, Super Mario Sunshine, and especially Super Mario Galaxy. Koopas and Shy Guys are just generic enemies who have no important roles in the storylines like Toad and generic Toads do. Yoshis and Toads are the only generic species to be playable outside of spin-off games.
Edit
Actually, he took the son's place. Mario was the one who took Papa's place.
That is incorrect. Toad did replace Papa, not Imajin. Here is the link comparing Doki Doki Panic to Super Mario Bros. 2.
http://themushroomkingdom.net/smb2_ddp.shtml