- In FE12, Marth of course was the main character. But we also had My Unit, whose official artwork which appeared on the boxart looks very similar to Ike. How convenient, Marth and "Ike" are both on the boxart as a result.
- In FE13, we get another Ike lookalike in the form of Krom. Krom even has a similar backstory, since he's the leader of a small but skilled combat group, and he has a younger sister who's a cleric. Krom wields a Falchion, which is Marth's signature weapon. Speaking of Marth, one of the main characters is "Masked Marth" who claims to be the real Marth.
So once again, two of the game's most important characters are people who resemble (or are) Marth and Ike.
Additionally, FE13 introduced DLC to the series. It was inevitable that Marth, Roy, Ike, and Lyn would all show up eventually via this in one way or another, but it happened even faster than I expected. Traditional Marth was the first main DLC character announced and given a big revamp, with Roy being tied for second with Leaf. Roy's design makes him look very badass, while Marth's makes him look like a girl, which are likely references to how Smash Bros fans perceive them. Additionally, Ike and Lyn cameo in Marth's joining chapter and there's little doubt in my mind that Ike will be in the next batch of recruitable DLC.
Overall, this isn't too much of a bad thing. Ironically, it hurts SSB4 the most because all of the important characters from FE13 are too similar to characters already in Brawl, so they either have to boot an existing character or add someone not as important or relevant.