How to Unlock Characters
Main things I’ve come across is that I had to use the original Peglin character to unlock them.
The spinfection peglin is easiest to get on the final boss that eats you in the castle. The orb that looks like a witch’s hat and the spinfection doubling orbs are the best for that as well as a thinner deck so you can get back to them quicker. The relic gloves that add spinfection on attack also help.
The balladin peglin was the most difficult for me, but I think the same boss as above is probably the easiest one to get it on (primarily because he doesn’t actually attack you so you really just need to ensure you win as long as you have some orbs that will give you the enough of the shield buff). I don’t remember the orbs I used though.
The spinvention peglin is pretty easy since there are now 4 or 5 orbs that will apply some manner of slime on the pegs, not to mention relics that also add slime. It doesn’t need to be the same type of slime that it bounces between either. Funnily enough, I got it on the same boss as above. Main reason that boss is so good for this one and the balladin is that there are so many pegs in close proximity. The orbs that place a slime will say so, but they also have similar looks (you’ll see what I mean) that makes it easier to identify them quickly.