I'll say this first before I give some feedback, that the two of you seemed evenly matched. You had a good number of reads on him that definitely helped with the fights. Also, where these 5 the only fights you had or they only ones recorded? Reason I ask is because your video titles mention 8, 12, 13 and so on so I wasn't sure if you fought the same player 13 times in a row or if you were in a type of tournament or round robin style group setup and these where the only times you could adapt to Fratos. Some of my criticism would seem less important depending on the answer.
Alright, first observation was that you spent quite a bit of time doing short hop n-air and f-air when your opponent was just standing on the other side of the field. This was more prominent in the first 3 videos than the later ones. I noticed that Fratos would start baiting those for Quick attacks later on to start racking up damage. I know that Ike's N-air has extremely low lag, but it's still there. There were quite a few times where having your feet planted on the ground would have given you much more options against him than in the air, where Pikachu can out maneuver you.
A large portion of your approaches where jump attacks, when Fratos would often block and either regain field control or punish you for. More empty short hops and grabs would have helped shake things up and allowed for more opportunities to punish. You started adapted to this in the last 3 videos more, which helped your matches but you still spend a lot more time in the air than I'd recommend against a Pikachu.
I noticed you favor jumping from the ledge quite often, which after 2 matches your opponent started anticipating and punished for. A few more from ledge attacks would have helped out in putting some fear in him when you recovered.
When Pikachu was off stage or ledge hopping, you would almost always go off stage after him, whether above or below you. I'll admit that you are much braver than I am when it comes to such, as when you were able to read his recoveries in to the air you nailed him good. After a couple of matches though he started using that to his advantage. He'd be able to quick attack around or through you often and leave you struggling to get back. Mixing in some Aethers from the ledge when he was approaching from the side or Eruptions from below would have made you harder to predict and returning to the stage much more fearful. I've read from other tournament players (and have dabbled myself) that Ike's Eruption from low is a terrifying thing, especially if you are right up to the ledge. Reason is that the tip of the sword adds more to your hitbox and goes even lower than the actual explosion, which may have allowed you to sneak a hit in between when his quick attack fired toward the ledge and the actual ledge grab happened. I know that if Fratos tried to Quick Attack from higher it's not so reliable, but from below it's much harder to avoid.
After a while, Fratos was catching on to how you were almost always using QD when returning from the stage above it and was starting to anticipate that. Mix in some fast falls (and if needed into Counter or Blocks) would have shaken him up more.
Last thing I can recommend is to slow down a little. Ike's rushdown is decent, but Pikachu's is better. There where quite a few times where walking would have been much more beneficial, since you could have easily have stopped his dash attacks and running grabs with a jab, dtilt or set him up for a juggle. Now I'm not saying you have to completely change your playstyle, but sometimes slowing down can give you much more perspective when against fast opponents. Example, Fratos liked to go from dashing to a short hop n-air quite often, which you could have ducked under and punished since without a shield or body in the way he would have continued sailing over you. (Ike's got one hell of a duck for a heavy! I've even ducked under Pikachu's thunderbolt on occasion.)
I know this looks like a wall of text, but in actuality it's more nitpicking. You did a good job adapting against your opponent from what I could see in the video. All you need is the ability to mix it up a little to throw off your opponent (since he was getting conditioned to your tells) and you would not only have own but decimated. It was a fun set of matches to watch.
. Cannonballs are easy to get around, and some of his smashes have a bad enough windup to avoid easily. I'm still figuring out my best options when he does his go-kart drive or ejection. For the go-kart, I like to either short hop n-air or counter depending on the distance he's trying to cover. Neither feel like an great option though. As for the ejection, his hammer attack is pretty fast which I haven't found a good way to bait for anything substantial yet. My gut instinct tells me it's fairly even, with maybe Junior having a slight advantage due to his zoning and dash attack speed.
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