Use your aerials to keep projectiles off you. Power shielding them also works, you want to get in and keep them in. For approaching I recommend either trying to get a grab or go for a spaced SH aerial, Ike has pretty good options out of a SH and Nair doesn't have much landing lag so it isn't punishable. Spaced FAir is safe on block as well so you can space out DHD and Samus with it because of Ragnell. For DHD I recommend swatting the can away and try to land it on his lap, it'll blow up in his face. Clay Pigeon should be hit before it explodes or it'll hit your shield. Watch out for DHD's hitboxes, they are weird so you have to get used to them. Just space out aerials and remove their projectiles, like you would in P:M. Ike doesn't have many options against projectile heavy characters so you have to be patient without taking too much free damage.
) any advice for getting in on characters like Samus, Duck Hunt, Link etc.?
