Thank you for the message, I'm glad you're finding joy with the game, SGreymon Ruin mode and Examon X are not in the game, mametyramon was taken out of the agumon digitama but it can be made through jogress using the next digimon as material:
(Tyranomon + any Mamemon) or (Monochromon + Ebidramon), or (Shellmon + Monochromon), or (Ebidramon + Shellmon);
You can find every jogress in the game as well as it's material in the game's discord and if you have any trouble or question you can freely ask there. I hope to continue bringing improvements to the game for more enjoyment.