Is wxm023b Cerise (from Wolverine and the X-men set) a regular figure I can use on any team I build? Or does she need to begin as deathbird, then on the game choose Cesire? I don't understand the b at 023b Cerise and I see an a after 023a Deathbird.

Is she a spacial character like the alter identity?

If it is like any other character, then this character is excellent. She can have energy shield at the same time she has combat reflexes.

She is a prime rarity figure meaning that she can not be played with any other Prime figure on the same team, but she does not need to be played with Deathbird.

Cerise and Deathbird are not alter-ego figures.

They can each be a part of any team and have no special interaction powers between them.

They are completely different figures and are numbered a & b since Cerise is a Prime (green ring). You may only have one Prime figure on your force.

What Mikethered and redking said. And yes, Cerise is an amazing figure, I love having Combat Reflexes and ESD at the same time.

Dude, I'm not even overweight!

XD I'm on a Mac, so goddang autocorrect screws me up every time.
Edit: Fixed my original post as well.

Is the htB010 Security Guard (DC Bystander) a Prime Figure as well?

Meaning there can be only one of him in a team?

and if so I would not be able to use Cerise, Right?

From the Players Guide, Section 1, Page 3:
So any number of green-ringed Bystanders CAN be on the same force as one green-ringed figure.

(the latest rules documents are always available at http://heroclix.com/downloads/heroclix-rules)