im saying snake is a definite MK counter.
zelda has a big advantage over MK, the dins fire can be avoided but it kills your aerial game. her smashes last for a long time and have high priority making it hard to get in. just dodge a dins fire and punish her before she gets a smash off. combo her to death or punish her when she tries to recover. her upB has start up lag, get a shuttle loop in there before she teleports and shes toast.
falco is going to cause a lot of problems along with wolf, but them being severe counters im not too sure of.
pit is not a counter to MK, his arrows are easily avoidable and MKs ability to chase pit off the stage and hit him while hes using his upB gives MK a huge advantage.
pikachus thunder is a big problem, it last for a while so its hard to get by it when recovering and MKs air dodge doesnt last too long and may not always make it past the thunder. pikachus got a quick fair to dsmash which can cause problems, but you can DI out of the dsmash. pikachus fair and dair have better priority than MKs aerials and glide attack. i still wouldnt say pikachu is a counter to MK. MK is faster and can get the kill on pikachu quicker, hes definately a fighter, but not a counter.
ROB gets tooled on by MK, the laser and gyro are too easily avoidable and ROB doesnt have the speed to match him. im with chozenone, MK is a counter to ROB.
DK doesnt counter MK. you can avoid his power. id put DK on the level with ROB against MK and say MK has an advantage over DK.
Link/Toon Link is tricky against MK with his bombs, boomerang, and arrows. not a counter just requires you to think and airdodge alot. if youre a half way decent MK you shouldnt have too much of a problem getting around this, just play a link/toon link frequently and youll be good.
Bowser is not a counter.
in conclusion admiral bowser and any other MK player, you cant go on thinking everyone is a counter to MK just because theyre heavier, stronger, and have projectiles. that would put MK as the worst character in the game, but for some reason he is recognized as one of the best so far. why? because all those characters you can plow through with your speed and recovery. MK can KO pretty quick, even the heavier characters, you just got to play smart and trap them into your combos which should finish with one of his few but good KO moves.