He's got to be an avoidant but high damage output character, one of the abilities of kerbals is asexual reproduction so you have to incorporate an element of ice climbers, the idea is that your down ability doubles your amount of kerbals, the up halves the amount of kerbals.

The two other of the kerbal abilites could be based upon linking the kerbals together or distributing their momentum evenly between all of them(at a constant rate, in a vector directly away from the center of the stage) but if you just move about they move like the game with stopmotion where you kill yourself a lot, swapper I think?

Left ability pulls all the kerbals towards their current center of gravity, right ability pushes all the kerbals away from the center of the stage. Up splits each kerbal into two, down causes the kerbals to run towards the nearest kerbal and make a new kerbal.

Kerbals obviously can re-make a kerbal with the goo left over after excessive G-force exposure, and they have strut technology so there's no reason to suggest in the fare future(when kerbals have flown across the galaxy to collaborate with Nintendo) they will have electro-strut technology so it all makes sense in the canon.

Make the kerbal item just like a pokeball but spawning a random rocket.

Every one of their attacks is a headbutt, make the smash attack in any direction just have the kerbal do a semi-random headbutt motion all around in a circle. Idea is to cause chaos and make a lot of the death particle effects, more then anything else. And as your kerbals die you lose track of where they all are and you just have little mini-kerbals running all about the place.