Each character varies towards different letter, and the trait (of what the character they stand for) will be given to them if capitalized.

e.g. the letter "H" will grow ponytails as it is a trait from Hatsune-Miku

A group of people are all in a race on which the 26 characters must be filled up in 26 slots

Here are what they chosed for:

A is for Aquad (Mixels)

B is for Bernie (Zig and Sharko)

C is for Carl the NPC (NPCs are becoming Smart!)

D is for Doge (Memes)

E is for Entbrat (My Singing Monsters)

F is for Figure (Doors)

G is for Goliath (Devil May Cry 5) *

H is for Hatsune Miku (Vocaloid) *

I is for Inflatable apple

J is for Jon Arbuckle (Garfield)

K is for Kissy Missy (Poppy Playtime)

L is for Luxo JR (Pixar)

M is for Matt (Wii)

N is for Navy (Algicosathalon)

O is for Opium Bird (A.I) *

P is for Pin (Battle for Dream Island)

Q is for Qingque (Honkai Star Rail)

R is for Reemus (Ballards of Reemus)

S is for Sazae San (Sazae-San) *

T is for Ti West *

U is for Urial

More to come! (V-Z)

KEY:

*=These letters are found in the GHOST Challenge on which the audience must guess the character that start of a certain character

Check out the full series on the link here