Werewolf Chess

Here a nice sharp game with the Werewolf:

https://www.chess.com/clubs/forum/view/bulldog-chess-witch-and-werewolf-deeper-thinking-evert823

Very good idea

It was originally posted at chessvariants.com, where you can also use the diagram of the initial setup as a sparring partner to play against.

This method for preserving a certain piece type was taken from Maka Dai Dai Shogi.

I'm not able to find this point on wikipedia:

https://en.wikipedia.org/wiki/Maka_dai_dai_shogi

It is in the section 'promotion'; the Buddhist Spirit and Teaching King are the contageous pieces:

"Any piece, promoted or not, that captures a Deva or teaching king (a promoted Deva) promotes to a teaching king. This is effected by replacing it on the board with the captured piece. Similarly, any piece that captures a dark spirit or Buddhist spirit (a promoted dark spirit) promotes to a Buddhist spirit. The only exception is (potentially) royal pieces (emperors, kings, princes, and drunk elephants) which promote to their normal promoted forms, or stay as they are if already promoted."

Do the large Shogi variants give us any notation convention for double capture, or for capture and move on to another square than were you captured?

WinBoard uses notations like Wxe4xd5 or Wxe4-d5 in PGN for a double capture or a hit-and-run capture with Werewolf, respectively. Or Nxe4-d5 for a Lion in Chu Shogi, where it uses N for lioN, as L was already taken for Lance. For the larger variants the alphabet is not large enough anyway, and WinBoard uses L! for Lion.

how do you find it in variants

You can play it in forum games like we did here.

Does this make sense?

The Angel grants immunity to Werewolf contageon. That means: When a piece takes a foe Werewolf on a square where a friendly Angel grants immunity, the piece won't turn into a Werewolf.