I rolled a +HP / -Spd Ike, which at first glance is terrible. But it's actually not that bad. Ike's speed is already low. His most important stats are his attack and his defense. But you also definitely don't want to get doubled by casters either. He basically has the same stats as Ephraim who is S rank, a few pts more actually. I LOVE Ephraim's performance.
So I'm leaning towards Fury 3 in the A slot in order to make up for the lost speed. If you got a -Atk, -Spd, or -Def Ike then any of those respective +3 stats from your bane would be a decent choice. +3 Res wouldn't even be a bad choice either since his res is so low. Every time you can keep him up during a combat he's going to get a counter.
For B slot I'm thinking either Quick Riposte 3, Vantage 3, or possibly even Renewal 3. QR3 seems like the best option but it's also the least available. Renewal will counteract the Fury damage and keep him up longer in every instance. Vantage 3 or Renewal 3 is probably the choice here.
C slot you can use whatever. Focus your points on A and B first. You should get a positioning assist next too, either Reposition, Swap, or Draw Back. C slot doesn't really matter. I would pick something that will increase his survivability like Threaten Speed 3. Threaten Def 3 is a good choice too as it will help him take down other units.
Being that he's a red sword physical infantry tank, I lean towards survival abilities in most instances. Ike is a strong defender.