The EShop Button has been changed to the Mod Manager Button

(Credit to Volya, https://gamebanana.com/members/1486892)

(Mod can be found here: https://gamebanana.com/mods/369494) 

Tips in general have been updated to be more helpful and descriptive
The general smash attack charging sound effect has been replaced with the Brawl Sound Effect

Mario now uses a redesigned skin based on his appearances in Super Mario 3D World and Mario Odyssey.
(Credit to MaroonRed, https://gamebanana.com/members/1806514)
(Mod can be found here: https://gamebanana.com/mods/363538)

Alt 1 is the default Reimaged Mario

Alt 2 is a Fire Mario Alt

Alt 3 is a Wario Alt

Alt 4 is an NES Golf Alt

Alt 5 is Clown Mario

Alt 6 is Builder Mario

Alt 7 is Flying Mario from Super Mario Galaxy

Alt 8 is Wedding Mario

Up Tilt has a 10% chance of giving off a coin on hit, and a 1% chance of giving a purple coin on hit

Fair now has Fire Effects 

N/A

Samus’s Odd Alts have been replaced with Reinvisioned Samus, and Samus’s Even Alts have been replaced with Metroid Dread Samus

(Credit to Noababoa: https://gamebanana.com/members/1696475)
(Mod can be found here: https://gamebanana.com/mods/362715)

(Credit to LN_310: https://gamebanana.com/members/1723947)
(Mod can be found here: https://gamebanana.com/mods/326774)

Alt 1 is the Reinvisioned Varia Suit

Alt 2 is the Dread Suit

Alt 3 is the Reinvisioned 8 Bit Power Suit

Alt 4 is the Dread Varia Suit

Alt 5 is the Reinvisioned Gravity Suit

Alt 6 is the Dread Gravity Suit

Alt 7 is the Reinvisioned Light Suit

Alt 8 is an E.M.M.I. Dread Suit

Booster Effect no longer shows up on Shorthop

Samus's Forward and Up Smash use Ice Effects

All Fire Effects are replaced with Plasma Effects

Alt 2 has been replaced with the Varia Suit Alt
(Credit to Crim~: https://gamebanana.com/members/1498104)
(Mod can be found here: https://gamebanana.com/mods/175472)

Alt 4 has been replaced with a Metroid Dread Inspired Alt
(Credit to LN_310: https://gamebanana.com/members/1723947)
(Mod can be found here: https://gamebanana.com/mods/334969)

Dark Samus now uses their voice from Metroid Prime 2: Echoes
(Credit to BruhLookAtThis: https://gamebanana.com/members/1505299)
(Mod can be found here: https://gamebanana.com/sounds/45361)

Most of Dark Samus’s misc animations that were the same as Samus have been reanimated to be distinct from Samus

Down Taunt is now a maniacal laugh

Alt 3 has been replaced with Boshi, from Super Mario RPG
(Credit to Ilagu: https://gamebanana.com/members/1712987)
(Mod can be found here: https://gamebanana.com/mods/174235)

Alt 8 has been replaced with Black Yoshi

(Credit to ElevenZM: https://twitter.com/elevenzm)

(Mod can be found here: https://gamebanana.com/mods/174236)

Yoshi now has rainbow trails for his tilts

Kirby’s Inhale SFX have been changed to the modern Inhale SFX
(Credit to DShipps: https://gamebanana.com/members/2015234)
(Mod can be found here: https://gamebanana.com/sounds/59044)

Kirby now has rainbow attack trails for his foot attacks

N/A

Alt 6 has been replaced with a Detective Pikachu Alt
(Credit to Asalazar: https://gamebanana.com/members/1935258)
(Mod can be found here: https://gamebanana.com/mods/331230)

Pikachu now uses their Pokken Voice
(Credit to Nin10Doug: https://gamebanana.com/members/1478155)
(Mod can be found here: https://gamebanana.com/sounds/48834)

Pikachu’s effects are now colored Yellow

(Credit to Nin10Doug: https://gamebanana.com/members/1478155)

(Mod can be found here: https://gamebanana.com/mods/12847) 

Alt 3 has been replaced with Casino Luigi
(Credit to KantoSkies: https://gamebanana.com/members/1490431)
(Mod can be found here: https://gamebanana.com/mods/174135)

Alt 8 has been replaced with Mr. L

(Credit to KantoSkies: https://gamebanana.com/members/1490431)

(Mod can be found here: https://gamebanana.com/mods/306214) 

Ness now uses PK Rockin Effects for his normals
(Credit to Starrmax: https://gamebanana.com/members/1507325)
(Mod can be found here: https://gamebanana.com/mods/12840)

Ness’s Bat will glow with PSI Effects when fully charging F Smash

Ness’s Face turns into the entrance animation face when fully charging F Smash

Alt 2 has been replaced with Ramen Shop Falcon
(Credit to LN_310: https://gamebanana.com/members/1723947)
(Mod can be found here: https://gamebanana.com/mods/338409)

Alt 6 has been replaced with Afro Falcon
(Credit to SeanB: https://gamebanana.com/members/1513485)
(Mod can be found here: https://gamebanana.com/mods/174743)

Falcon will say “Yes, Come On” if you parry a move.

Falcon exclaims “Yes” if he lands the sweetspot of Fair

When landing a Falcon Punch, the in-game crowd cheers for Falcon
(This also happens if Kirby copies Falcon and he lands Falcon Punch) 

Alt 2 has been replaced with Monocle Jigglypuff

(Credit to Devory: https://gamebanana.com/members/1480922)

(Mod can be found here: https://gamebanana.com/mods/292862)