I play Ike, Samus, Marth and Sheik often. From my knowledge:
-Ike is super prone to mindgames. Blaster forces approaches, and Ike is a defensive character. A well-timed Wolf Flash can go above Ike's edgeguarding U-Smash. Dair is a really good short hop option due to Wolf's air mobility vs. Ike's laggy attacks. I usually start combos with Dair, then mindgame with short dash dash attacks, Side Smash and shields until he Side Smashes at the wrong time. Only concern is his quick jab, but shine can break that quickly. Once airborne, angled uair's avoid all of Ike's aerials, including Dair, and Bair takes full advantage of his poor recovery. His invincibility frames make Dair very hard to spike with while he's recovering, so I prefer to edgeguard him with the Blaster, Bair and D-Smash.
-Sheik is faster on a number of attacks, but her weakest spot is her spacing. Wolf can outspace her with S-tilt and S-Smash and can punish her with Uair in the air due to her lack of effective counters. Her side smash is avoidable easily with timing and U-Smash on the edge usually spells doom for her. Just avoid her jab range and space yourself when parallel to her in the air, because Bair and Fair on Wolf outrange Sheik's equivalents...but her's outspeed and can break your combos. Her recovery is easy to spike with a short hop Dair if timed properly after she appears.
-Samus loves those projectiles. Shine is an easy answer. The Samus I usually play likes to use bombs to float herself to avoid juggles and get her bearings, but Up-B or a well-timed Side B is a good counter. Samus has a dangerous spike so its good to keep Wolf above her or to the left or right. Bair works as always, although fair is somewhat weak on such a heavy character and may be insufficient. Like Ike, short hop dairs on the ground exploit her terrible upward options. Blaster can build damage, but well-timed Charge Shots can cancel them out, so short hopping over them and then using the Blaster before using a jab and a follow-up combo is your best option.
-Marth has superior spacing and his Counter is super annoying. Mindgames are a must. I usually use Blaster to force an approach, then back hop - Blaster on the counter to feign a melee attack and retaliate quickly with a Side-Smash. Wolf's air mobility lets him dance around Marth's dangerous aerials and score bairs and fairs all day. Marth's Side-Smash is a dangerous edge guard move. I usually aim for Wolf Flash onto the edge, and then quickly use my get-up attack to avoid being tipped by the Smash (which can hit even while you're on the edge). If not, I Wolf Flash above his head and roll to the side to try for a quick combo. Marth is definitely dangerous, but Wolf's greater mobility is what you need to exploit. A good roll will avoid Sword Dance, and a well-timed shield can block Dolphin Slash.