Ike is a fine doubles partner, I recommend pairing with either a speedy, combo character or a good projectile-zoner. Preferably don't pair with another bruiser, unless you guys have some amazing strats.
Double-bruiser can work, but if the other team knows what's up, you guys may end up divided and conquered.
My doubles partner is usually DDD or Mario, and occasionally when he switches to Wario or Bowser, I'll swap to Marth or Link.
Though Wario and Ike can work if the opponents projectile game isn't too strong.
Though really, the key is to figure out where your partner is comfortable and cover his/her back. I tend to take most of the ground game and let him take the air, since QD and grab can usually cover the ground better than most of his options, taking to the air occasionally to edge-guard and complete combos.