Here's a shot at Captain Britain. Yes, the bonding is a bit forced, but it hits all the principals as well as most of the other folks that have been associated with the team at some point, without being too out of control. The basic mechanic is borrowed from Frankenstein.
I went with the more recent "power from confidence" thing because it's more fun, even though it doesn't coincide with the original Excalibur comics. I'd certainly entertain other ideas for the second power.
NAME = CAPTAIN BRITAIN
SECRET IDENTITY = BRIAN BRADDOCK
SPECIES = HUMAN
UNIQUENESS = UNIQUE HERO
CLASS = LEADER
PERSONALITY = SELF-DOUBTING
SIZE/HEIGHT = MEDIUM 5
LIFE = 6
MOVE = 6
RANGE = 1
ATTACK = 7
DEFENSE = 6
POINTS= 280
EXCALIBUR COMMANDER
After revealing an Order Marker on this card and taking a turn with Captain Britain, if Captain Britain is engaged, you may take a turn with a Unique Hero you control within 6 clear sight spaces of Captain Britain that is a Protector, Recluse, or Telepath.
SELF-DOUBT
When Captain Britain attacks with a normal attack, if he does not inflict at least 1 wound, then place a self-doubt marker on this card, up to a maximum of three. Reduce Captain Britain's attack and defense by 1 for each self-doubt marker on this card. If three Self-Doubt Markers are on this card, Captain Britain cannot use his Flying or Super-Strength powers. If Captain Britain inflicts a wound when attacking with a normal attack, remove a self-doubt marker from this card.
FLYING
SUPER STRENGTH
Here's the list of bonding targets for the "Protector, Recluse, or Mutant Telepath":
Of course Meggan would join that, and presumably Rachel Summers would be a Mutant Telepath if we made her. The currently listed version that strips the Mutant qualifier away allows bonding with Gypsy, Manchester Black, and some Simians and Martians (notably Martian Manhunter).
Earlier version of the bonding power that shuts out non-Mutant Protectors (Angel (Liam), Captain Marvel (Genis-Vell), Falcon, Iron Man Mark III, Red Tornado, and Witchblade) and Recluses (Cloak and Obsidian), but allows scientists: