Okay, first some pros and cons to Marth.
Pros:
- He is very fast, one of the fastest in the game.
- His attacks have very high priority, meaning that if 2 attacks face off, his will probably win over.
- If you connect with the tip of his sword, it deals more damage.
- Fast side special, most combos of a special too.
- Great aerials, fast and high priority, he gets 2 Fairs (Forward Aerial) with one shorthop (small jump).
Cons:
- He is very easily killed, b/c he is lightweight.
- His specials are not that useful, you'll be mainly using his A attacks anyway.
- Counter leaves you wide open if failed.
- Pretty bad recovery, you can only use side b and up b, low vertical and horizontal recovery.
- No projectile
Good Moves:
- Fair - fast, good damage, high priority, good edgeguard.
- Fsmash - fast smash, great damage, high knockback if tipped.
- Dtilt - can poke through shields sometimes, longish range
- Nair - great defensive and offense move
- Dair - can spike an enemy if tipped
- Throws - useful for comboing
Combos:
- Basic combo - start off with a grab or a neutral A, then follow up with Fairs and Nairs, end with a Fsmash.
- Ken combo - shorthop fairs, ending with a spike with the dair or just a tipped Fsmash.
- Juggling - keep them in the air with your f,b,u,and nairs, end with a Fsmash.
- Techniques:
- Vertical Spacing - Use a footstool hop, then quickly use a dair. This will provide space for a spike, seeing how the spike is hard to land. Pretty tricky.
- Shorthop - Let go of the jump button faster, you will do a smaller jump
- Counter - when used correctly, can be very effective, good for mindgames also.