I am a longtime fan of the Super Smash Bros series every since the N64 Version and i must say while the roster is satisfying it is clearly lacking in some of the characters, ill do this by going by series
Mario Bros Series
1. Waluigi
Mario has his rival but Luigi's rival was omitted, for one another big character in general isn't a bad thing especially since he'd have awesome reach, tell me you wouldn't want to do a 4 way brawl with Mario, Luigi, Wario, and Waluigi.
2. Toad
Toad has been with the Mario series on countless games, he's always been an interesting character and his addition would be very nice
3. Geno
Geno was actually in a Mario RPG(one i've never played), i think having a character from a mario fighting game would be interesting and i know for a fact Geno has a wide fanbase in Japan
4. Paper Mario
I know what you're thinking another mario, but i think his introduction would be interesting and he'd have a completely different moveset from mario making him in alot of ways his own character
5. Birdo
Mario has his love interest peach, but Yoshi is lacking in that department
Zelda Series
1. Ghirahim
A big Zelda villian i think his/her introduction would be welcome a great swordsman and a demon lord
2. Yuga
Yuga is Ganondorfs counterpart in a link between worlds a powerful wizard and his/her finals mash could be merging with Ganon
Megaman Series
1. Megaman X
Lets just be completely honest here, Megaman is nothing compared to Megaman X who is way more badass and has tons of powers i mean hell his final smash could even by the Houdoken
2. Zero
Just as cool as megaman X is Zero who would be a great addition to the roster
3. Sigma
A big villian in a number of Megaman X games, his addition would be really cool
4. Vile
Vile was the first big boss in Megaman X he was so powerful before you upgraded you coudln't even touch him
Sonic Series
1. Knuckles
Essentially a slower more powerful Sonic, but completely badass, he reminds me of trunks from dbz
2. Dr. Robotnik
Sonic deserves the right to battle his rival
Punchout Series
1. Mike Tyson
Playing Mike Tyson would be really cool a Tyson vs Lil Mac would be fun to do on max difficulty
Donkey Kong Series
1. King K Rool
Donkey Kong's rival would be fun to play as and another big character
2. Funky Kong
With Donkey Kong, Diddy Kong, King K Rool and Funky Kong you'd have a fun 4 way smash
Kirby Series
1. Waddle Dee
Waddle Dee would be fun especially since he has a spear, and this was supposed to be leaked in that video that has Mewtwo, Wolf, and Waddle Dee
Mario Bros Series
1. Waluigi
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Mario has his rival but Luigi's rival was omitted, for one another big character in general isn't a bad thing especially since he'd have awesome reach, tell me you wouldn't want to do a 4 way brawl with Mario, Luigi, Wario, and Waluigi.
2. Toad
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Toad has been with the Mario series on countless games, he's always been an interesting character and his addition would be very nice
3. Geno
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Geno was actually in a Mario RPG(one i've never played), i think having a character from a mario fighting game would be interesting and i know for a fact Geno has a wide fanbase in Japan
4. Paper Mario
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I know what you're thinking another mario, but i think his introduction would be interesting and he'd have a completely different moveset from mario making him in alot of ways his own character
5. Birdo
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Mario has his love interest peach, but Yoshi is lacking in that department
Zelda Series
1. Ghirahim
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A big Zelda villian i think his/her introduction would be welcome a great swordsman and a demon lord
2. Yuga
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Yuga is Ganondorfs counterpart in a link between worlds a powerful wizard and his/her finals mash could be merging with Ganon
Megaman Series
1. Megaman X
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Lets just be completely honest here, Megaman is nothing compared to Megaman X who is way more badass and has tons of powers i mean hell his final smash could even by the Houdoken
2. Zero
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Just as cool as megaman X is Zero who would be a great addition to the roster
3. Sigma
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A big villian in a number of Megaman X games, his addition would be really cool
4. Vile
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Vile was the first big boss in Megaman X he was so powerful before you upgraded you coudln't even touch him
Sonic Series
1. Knuckles
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Essentially a slower more powerful Sonic, but completely badass, he reminds me of trunks from dbz
2. Dr. Robotnik
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Sonic deserves the right to battle his rival
Punchout Series
1. Mike Tyson
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Playing Mike Tyson would be really cool a Tyson vs Lil Mac would be fun to do on max difficulty
Donkey Kong Series
1. King K Rool
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Donkey Kong's rival would be fun to play as and another big character
2. Funky Kong
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With Donkey Kong, Diddy Kong, King K Rool and Funky Kong you'd have a fun 4 way smash
Kirby Series
1. Waddle Dee
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Waddle Dee would be fun especially since he has a spear, and this was supposed to be leaked in that video that has Mewtwo, Wolf, and Waddle Dee