Well i don't know how to really explain how I deal with them XD.I've beaten some great MKs and Snakes on AiB.
Snake really isn't to hard for me.I play aggressively,so the snakes I usually play like to try and counter my approach with ftilts and the like.Once I get past those ftilts I usually pull off some good combos on em and rack up the damage.The key is just watch those tilts and that slied thing he does with the fsmash.
I'm in the air with kirby alot,so I usually expect a snake to come sliding towards me with a usmash.Luckily for me,dair blows through the usmash missle from Snake easily,but don't get to careless doing that.
Meta knight,I usually approach with a nice fair or dash attack.Meta knights aren't really hard for me,it's just the speed and higher priority moves I have to watch out for,such as nado spam alot of mk's do.I manage to get out of them though almost all the time.
Dgrab them when you get the chance.Most of the time most mk's will dair as soon as they get out of dgrab,so you get another free grab.If not just follow up with a Uair.
When recovering,I jump and fair as that is pretty hard to get by,they almost always get hit with the 2nd or last hit.
When edge guarding,jump and fair if they are trying to glide down.I also like to use rock if they are climbing back on the stage,or even final cutter for when they use side b.