Samus is alone because no other notable characters can realistically work right now.
Mother Brain? Nope.
Ridley? Nope.
Kraid? Sorry.
Dark Samus? Sure, but she'll be very cloneish.
Sylux? Not notable enough.
I'd like Ridley to work, but he's super awkward to work with. Long tail, large wings, skinny limbs, the thing looks like a emaciated chicken carcass. He's super gnarly and has a ton of character, but the way he has to be significantly more airborne than others while not being either a punching bag (massive hurtbox because of the long tail/wings) or overpowered (heavy character with disjointed/large hitboxes) makes it hard to make a character around.
I can already hear the keyboards warming up, so let's put it this way.
You have to balance a character that must:
1. Feel strong.
2. Fly or stay airborne for a notable time.
3. Posses a projectile attack.
4. Have appendages proportionately large.
You have to do this while:
1. Not making him so light because of his long reach.
2. Not making him too heavy so he's a punching bag due to his size.
3.
Staying true to the character found in the games.
I'd start by choosing to sacrifice either his reach or his flight, but then we're getting into awkward territory. Ersatz's Ridley is either a strangely close range fighter or a grounded, winged kaiju.
In a way, Ridley fans (like me) should be glad that a director exists who won't half-step the character.IIt's not a satisfying choice to leave out the character, but sometimes doing nothing is best.
Take this post as my