I would recommend looking at my post:
4 Custom Factions - Evil Army , Swarm (TS Ready), Hackers (Print Ready) and Gunfighters (Print Ready)
And steal some ideas, if needed.
Deck is designed around destroying minions and gaining VP. Some cards have the theme of decks of playing cards (influenced by Red Dead Redemption)
What I saw was:
1 - Discard to destroy
2 - Lots of talents
3 - Extremely powerful specials.
The card mechanics must reflect the theme but be consistent enough.
( 4x ) CUNNING SCOUNDREL - 2 Power - Talent: Draw two cards and discard one of the cards you drew.
( 3x ) TRIGGER HAPPY COWBOY - 3 Power - Talent: Discard a card to destroy a monster of equal or less power than this one.
( 1x ) BILLY THE KID - 4 Power - Ongoing: When a minion is played on the same base as this one you may discard a card to destroy it.
( 1x ) FLINT WESTWOOD - 4 Power - Instead of discarding this card after a base scores, move it to another base instead. Special: Before a base scores you may discard a card and play this card on that base.
( 1x ) THE LONE RANGER - 6 Power - Talent: Move this minion to a base that has only one enemy minion on it. Destroy that minion and gain 1 VP.
CUNNING SCOUNDREL is too strong - Talent with draw is an overkill (not offset by disadvantage) - for instance "Talent: Discard the top card of your deck. Draw a card." is an overpowered talent for a 2p minion.
TRIGGER HAPPY COWBOY seems ok (tough 70% of smash up players dislike munchkin expansion)
Now the fearsome trio BILLY THE KID and THE LONE RANGER have too much destruction and disruption. FLINT WESTWOOD is a super pirateking + first mate (also OP)
( 2x ) TRIGGER FINGER - Special: When an opponent plays a minion you may discard one card and destroy it.
( 2x ) SLY SHUFFLE - Shuffle your discard pile into your deck and draw a card.
( 1x ) SHERIFF'S BADGE - Play on a minion you control. Talent: Move this minion to a base with an opponent's minion played on it.
( 1x ) WANTED POSTER - Play on an opponent's minion. If that minion is destroyed the destroyer gains 1 VP.
( 1x ) QUICK DRAW - Play two extra actions.
( 1x ) THE HIRED HAND - Choose one of your minions. Move that minion to a base that has an opponent's minion of equal or less power. Destroy it and return to the base you came from.
( 1x ) ACE IN THE HOLE - Choose an action card in your discard pile and play it as an extra action.
( 1x ) READ 'EM AND WEEP - Reveal your hand. If you have at least 5 cards and either all minions or all actions you gain 3 VP. Discard your hand.
TRIGGER FINGER is too cheap for a free to play unrestricted destruction card. Compare it to flame trap.
SLY SHUFFLE has a usable mechanic if you adjust the discard cards from your deck, like my suggestion on CUNNING SCOUNDREL.
SHERIFF'S BADGE is comparable to elves action strong, but can be played around.
WANTED POSTER is a bit too easy to play around the condition.
QUICK DRAW lacks a unique feel
THE HIRED HAND is a bit complicated for a simple (and overpowered effect)
ACE IN THE HOLE is a bit too time traveller-ish.
READ 'EM AND WEEP is a bit hard to pull off (3vp is way too much)
Basically your deck can:
Destruction (without any restriction)
Discard pile recovery/manipulation
Keep minion in play (like a first mate)
Those are too many kinds of effects (on top of several overpowered cards)
My next post will work on the ideas I liked.