I do tend to roll a bit too much in this matchup.
Like I said, don't roll. You know about zcanceling, so instead of rolling around you should be doing aerials.
My brother loves jumping above me into a dair/utilt/bair combo. If I dont intercept him while he is in the air, I am sure to take at least 20 percent.
Only 20%? Don't tell you brother, but he can easily rack that up to 60-70 % lol. Well you can try to intercept him with an uair, but if your brother has better spacing than you it might be tough to do. Another option is to not let him get above you. Use the platforms on whatever stage to stay above him and force him to either be below you or even with you.
When I recover, he tends to just air camp and as I recover high, I get spiked and if I recover low, I get spiked so I usually try to stick to the center of the stage.
He gimps pikachu extremely easily
This should never happen, and is strictly due to you being overly predictable. Pikachu has the best recover in the game by a mile, and should rarely, if ever, be gimped. You have so many options as pikachu, if he takes one away, use another one. If you try to recover high, and then he goes high, pull away and fastfall down, then up-b onto the stage. If he gets above you for the spike, go underneath or around him. You should work on effectively using up-b to go directly to the ledge. If you can do that, it forces him to cover that option leaving high recovery that much more open. You should also avoid floating down helplessly as much as possible. Try to finish your up-b near or on the ground so he has less time to catch up with you. Btw, if you release the stick right before the end of the up-b animation, you will actually go even further. This is useful if you are using it horizontally as it will get you further away from him.
My brother plays defensively, but when he approaches and plays offensively I have almost no options to defend as all of his aerials trade with mine.
A defensive Kirby can be very difficult to approach. You really have to bait them into making a false move and then capitalize. An example that works a lot at lower skill levels is to almost land right in front of them, but jump at the last second. A lot of players will automatically fsmash, and after you've avoided it you can usually punish them. Depending on how your brother likes to attack, try to make him think he'll be able to hit you, but avoid his attack and punish him for the attack you know is coming. I hope that makes sense. Also, if he's coming at you with a Dair or something, a well timed utilt while you are facing AWAY from him should stop him in his tracks and maybe lead to a combo for you.
Again, uair is pikachu's best move, and one of the, if not the best move in the game. Don't approach kirby with fair for sure, as that is a move that will almost always trade or get beat by kirby. Uair is your best bet. It comes out quickly, but it comes out back to front, so you should face away from him if you're trying to catch him before he attacks. You should try to do one of 2 things with an Uair approach: 1) Catch him before he gets a move off. This shouldn't be too hard if he is trying to do anything but Nair. Or 2) Use the approach to bait him into doing an aerial of his own, avoid it and counterattack. You shouldn't be traded as much as it sounds like you are. Back is also acceptable, but less as an approach and more as defense to keep him spaced away from you. Dair is strong, but doesn't have the best priority, so it should be used to finish a combo or as a punisher more than as an approach.
Shielding vs kirby is rarely a good idea. If he can land a hit on your shield, often he can break it. And since there is no good use for shield other than to absorb a hit, just don't shield vs kirby. Rare exception is if you are near a ledge and he is about to push you off.
