Generally worse than iron fist for same cost.
Iron fist does 2 stun+1 last hp block. He does 6 damage over 2 turns
Charlie does 1 block from toughness (can't attack first turn he comes out either)+1 last hp block. Charlie does 3 damage over 3 turns.
So Charlie has 1 fewer block, does 2 less damage over a longer period of time and has more conditions.
Only other best case scenario for Charlie (aside from other card combos) is blocking exactly 1 ATK hits (maybe from small Minions) and returning 1 damage each. Iron fist can't tank 5x 1 ATK hits while still doing 4 damage.
Iron Fist is one of the best allies in the game, so this is an unfortunate comparison. There are plenty of allies, even basic, that outclass Charlie though — Stretch22 · 249