In the shop, is it just to buy the recipe early on, or is it for the ingredients for the fusion ark?

It is to buy the recipes early on, but you can get all of the recipes by going on with the story and doing side quests. You do not get the ingredients whatsoever.

I have already got most of the recipes unlocked and I have 3 more missions left, probably more once I visit a few towns again after completing them. It’s a bit pricey to unlock something early. Done most of the game in less than a week.

Yeah some are kind of pricey and I really do not think you should buy any because you could use gold for better stuff such as gold eggs or 100% catch cards. I also finished the game within three days because I became so addicted

Dont buy any of them in the shop as u unlock them all through the quests

Another thing. I caught a D rank bluey and Galey, fully evolved them but boosted to rank C on Galey. Fused them and got a C rank typhoonwyrm. In PVP it shows that I have 2 rank E bluey and Galey fully evolved and a C typhoonwyrm. Why does it show them as 2 rank E and not a D and a C?

In PVP, all the fused arks you used automatically become E unless you have a duplicate on single player. For example if you have 1 magmawyrm (grade B) + typhoonwyrm (grade C) to make an Omegawyrm, you would get a grade B omegawyrm and then magmawyrm and typhoonwyrm would become grade E. If you wanted to keep the D and C grade of bluey and Galey then you would not want to fuse them. Hope this made sense

Ahh. Well there’s this Naga I just evolved. Got it rewarded as a class S and in Pvp it’s rank E.
Got it rewarded by playing pvp

Really? That is really weird. Might be a lag or bug. I am pretty sure all Arks you get from PVP are S grade.