hey

I want to play melee - but maybe put some int stat.

lets say if u had 4k for lvl55+ gear

what would be possible with which char? like would a melee guard with an average charm be able to pull of a decent mcc after lvl 55?

A guardian would work perfectly for what you are looking to do. I generally stat a guardian with a base of 70 vit and then do every other stat into intelligence. Then you need to spend fg on hybrid gear that has heal mastery/dexterity/strength on it as well as a weapon with high ee and heal mastery/dex/str on it if at all possible. With good setups, it is possible to do a full mcc.

This would work, but leveling will be really slow, because guardians don't do much damage. Unless you had an amazing ee club.

kill speed is maximised the same way whatever route you choose to take
can be tricky to achieve with melee and 1-5 hit kills is a big ask without looking at capped weaponry just as a starting block
you should have little trouble getting to the 6-10 min point per lvl with decent gear, faster will require excellent balance and items