if the opponent isn't good, just a simple fair or bair, or evne hair, will do the trick. try to practice your zoning so that you attack from the safest distance possible.
You can pursue people off-stage with side-B, since you can jump out of it. REMEMBER THIS.
try paying attention on how they react when you do it, see if they can't be baited for an airdodge and a heavier punish.
cannonball is interesting from far away for some characters that can't afford to airdodge and lose momentum, they will either take the hit and die, or use their recovery too early and be helpless.
mechakoopas being tossed is also great, practice with it. just dropping one to block low recoveries can work... and with practice, you cna do it with the cannonball's drop-off. (they will NEVEr see it coming. seriously)
Abandon ship can also work wonders. you can bait them with the ship and make them eat the explosion, or the hammer... there are many setups. people recovering high are very susceptible to upsmash, especially out of shield if they try to cover their recover with an attack. D-tilt can help you too since it eats airdodge thanks to lasting long.
oh, appparently, Down smash, and a down-angled Forward smash, can both do wonders... people recovering high to land on the actuall stage can eat any of the smashes, out of shield mostly.