Mario and his friends, Star World Humans, 4D counterparts
Dimentio and his minions
After Dimentio had been defeated, all the heroes from Blooper Land had done their job in the Fourth Dimension, gathering D-Stars and defeating Dimentio.
In Blooper Land, Starman3 threw a party in Blooper Land, but the problem was that the Fourth Dimension gangs can't go to the Blooper Land/Mushroom Kingdom Dimension. So they went to Star Road instead. Starman4 sent a letter to his counterpart, Starman3. Then Starman3 and his friends went to Star Road. And now Starman3 saw all Fourth Dimension gangs... but some of them are new that he has never seen before. So then, after the party Starman3 went back to his dimension. But then MarioMario54321 decided to tell Starman3 that MM54321 had a surprise for him, but he decided not to spoil it, so instead he dropped the hint. So Starman3 flew to the Star Road. Then he thought of something: trying to go to Game Over Arena. But then he crashed into the wall! Then he appeared in the SMSR Game Over Arena and went searching for the pipe that goes to Fourth Dimension. Starman3 got worried that it may not work for him, but he tried .....and guess what? It works! Starman3 made it to the Fourth Dimension! So that's why MarioMario54321 gave him the ability to go there. Then Starman3 talked to Quario and Fourigi about it and they actually agree with it. Starman4 told Starman3 something about HIMSELF. Starman4's mystery about himself had finally unfolded! Starman3 got surprised! Starman4 said, "My group's name is......... FOURTH DIMENSIONAL RANGERS!" And that's how Starman3 learned about Starman4's group! It's very similiar to the Youtube Rangers, being the 4D counterpart of 4DR.
Enzour AKA Prinplup44 (which is Enzo's 4D counterpart)
SuperQuarioGlitchy4 (Not Shown In Video)
SMUS84840 (Shown In SMUS16475'S Video)
Brynn2244 (Shown in SMUS16475'S VIdeo)
DoshiFanX54321 (Shown In SMUS16475'S VIDEO)
NikFourigi (Starman4's cousin but not shown in video)
QuatiosBoy4 (LatiosBoy5's 4D Counterparts; Also known as Jbro104) (Quit 4DR)
FightingQuario54321 (Not Shown)
LightQuacario104 (Not Shown)
QuarioGame4444 (Shown In MarioMario54321's "Into the Fourth Dimension")
And the rest of other 4DR members.
Starman4 claims to be the best counterpart friend with Starman3. And SM4 has one Elemental Star, which can do Dimensional Travel, which is similar to a Dimensional Backtravel Diamond! But he can only travel from the Fourth Dimension to Blooper Land. Unfortunately he can't go to the Star World. But he can bring his friends to Blooper Land, same as how Starman3 can bring his friends to Fourth Dimension.