Konami Soccer vs. Nintendo Soccer

Nintendo Soccer, April 9, 1985
Konami's Soccer, December, 1985

The dynamics of the ball is identical, so I think someone will have collaborated for both games.
And I doubt that Konami copied the game in so few months.

It's not for sure. The similarity with Mario is evident, however, it must be considered that in sports games Konami has used that face everywhere starting from Track & Field (Hyper Olympic) published in 1983. Certainly Mario was born in 1981.

Regarding the soccer I think the similarity with Mario was a coincidence of events. So the most correct consideration should be that Konami was reusing a format already known for Hyper Olympic, previously inspired by Mario. For sure, Nintendo could not have used that format for your soccer because it was already used by Konami in the other sports games previously released.

Here it is clearly seen that the faces of Konami's Soccer are the same of Hyper Olympic.

In this case it's not just about the characters. The entire game is almost identical. The prematch options menu is laid out the same with the same options, though Konami added the team names, and gameplay is also similar with that signature goal aiming arrow. Knowing Nintendo (and having dealt with them myself too), they are super fierce when it comes to any third-party using their IP or copying their games (well Konami is also protective but nowhere to the degree of Nintendo).

What would make sense to me is if there was one guy (or a few) who offered to develop the game to both companies, and ended up doing the Nintendo version first, then moved on to the MSX version, only this time applying more polish and some additional features after learning from the first version. This would also explain the small time window between the two releases, as doing a conversion is faster than doing a full game from scratch.

Takeru vending machines were installed in April 1985 and Konami's Soccer was the first game to be released in December. The game was probably ready in April, but between commercial agreements and distribution platform testing, it can be assumed that Konami came out late. Nintendo Soccer was released the same month as Takeru, thus taking advantage of the sale over Konami.