Logic Masters Deutschland e.V.

This is one large puzzle, consisting of four different variants of 6x6 sudokus, which are all linked together by the grey cells.

The following rules apply to the grey cells:
1) A black circle in a grey cell means that one of the two adjacent digits has the double value of the other digit.
2) A white circle means that the difference of the adjacent digits is exactly one.
3) A grey cell between digits 1 and 2 can contain either a white or black circle.
4) A "V" means the adjacent digits sum to 5.
5) A "X" means the adjacent digits sum to 10.
6) When two of the rules above apply to one grey cell, then both symbols are given. (The grey cells with black circles do not also contain a V or X.)
7) A hyphen (-) means none of the above rules apply to the adjacent cells. So all Vs, Xs and circles are given in the grey cells.

Normal 6x6 sudoku rules apply to all sudokus, so every row column and region must contain the digits 1 to 6.

Additional rules per variant:
Anti-knight: Cells that are a (chess) knight's step away from each other may not contain the same digit.
Non-consecutive: Any two orthogonally adjacent cells cannot contain consecutive digits.
No three odd/even in line: The maximum number of neighbouring odd digits as well as the maximum number of neighbouring even digits in any row or column is two.
Non-average: The number in a cell cannot equal the average of its two horizontal neighbours nor it equals the average of its two vertical neighbours.

The puzzle is also available on Penpa.

Enjoy solving :)