Ike vs Mr. Game & Watch is a very interesting match. Ike is the only member of the cast who can consistently outrange Mr. Game & Watch, but Mr. Game & Watch has so much going for him.
When fighting Ike, it's really important to go at him horizontally, not vertically. Ike's up smash, from an Ike with good timing, makes the key somewhat risky, and trying to fishbowl or up smash him as he comes down on you might be met with the lovely super armor of Eruption. The turtle has to worry about that jab combo a lot, but you beat out the first two hits of it solidly. However, if you get hit or shield the jab combo, do not try to retaliate. Ike will usually just do another jab combo to hit you out of your "counter". Backing off and approaching anew with the turtle is pretty much always best when Ike has you in trouble.
Ike is obviously pretty gimpable over the ledge. Jump out and forward aerial when he's charging Quick Draw; Ike either gets killed by the forward aerial or releases to his death (even if he hits you, he dies...).
One last thing, don't use down tilt against Ike. It's usually pretty handy, but it's very, very easy for Ike to move in and fsmash you if you get caught in some down tilts. Ike is pretty slow anyway; there's no reason to be shy about throwing out a few more than average forward and down smashes.
All in all, I'd say the matchup is even which is one of Ike's shining moments of pride (since Mr. Game & Watch is so good and all). Mr. Game & Watch has the speed, Ike has the range, and they both have the power.