First of all, Kirby is not a combo machine like Lloyd is. And certainly not fast paced, however, as this may be true that doesn't mean he can't keep up with the game, because Kirby just happens to be a lightweight All-around Character gifted with 6 total jumps. His strength and abilities also changes with who he's up against too.

Giving out an explanation on him on each an every single thing would be too long to answer your question. So i'll outline key factors that i think a Kirby main should know.

~Gotta manage your jumps properly.
~B-air is a really effective move, Spacing or attacking.
~Your edgeguarding skills are highly effective, only lacking projectiles but don't be afraid to get offstage to knock back the opponent.
~Gotta learn when to stop your string of attacks and space yourself properly so that the opponent doesn't get a free counter.
~Learn EVERY character's Neutral special attack. Learn how you can use their own ability against them and what times would it be useful.
~As always. Your opponents mistakes are your dreams come true. Punish them for this.
~Annoy your opponents with consistent "Haiiii!"

I may not be the best Kirby out there Certainly no T1mmy...or was it T0mmy? but i think this is pretty much a summarised version of what you need to know. If any other Kirby mains or general players see a fault in this you're welcome to point it out to me.

I'm absolutely loving Kirby. You can string together some really nice combos, especially off his up tilt. Obviously has an excellent edge game. Amazing recovery (as always). Very good aerials. Even his hammer is useful for a change. It can be pretty deadly if your'e accurate and good at short-hopping. He's elite IMO.

That's pretty much everything. I would recommend using Hammer as a spacing move to punish most wreckless approaches.

The hammer takes a short while to charge up, so it works best at high percentages. I personally prefer the air hammer because it charges faster, and while it does less knockback it's a good mix between speed and damage.

youll be surprised how effective randomly throwing out a grounded hammer can be

The Kirby hammer has lost me many friends.

Yeah. Random hammers is not a good thing. Why are people praising the hammer. It should be his least used move. *Maybe* for horizontal recovery when you are sky high and don't want to waste a jump but something I would not really use

no one expects the hammer, i use it very sparingly after about 5 minutes of being a campy a****** and people run right into it

...And here I just throw out random aerial hammers at least once every 20 seconds.

I really only hit the hammer on a hard read, or with like three levels of mindgames beforehand, or just as a sort of "I'm a complete butthole" way to punish. It's really a lot of timing.

Plus, the grounded hammer edgeguard is just so satisfying.

the best mindgame is being brainless

in short bursts of course

Hammer off the stage, wait for them to come back, hit them again, wait, hit, wait, hit, win. xD

Aerial Hammer's not as brainless as it used to be, but it's still very effective and comes out very quickly.

How good can kirby be if he is played aggressively? I might pick him up.

That depends on the matchup in my experience. Some characters its best to be more on the offensive side with, others its better to stay passive. Personally I tend to weave in and out of the two styles mid match when necessary, although most of the time I play more on the passive side.