So what are Quarters and Matchsticks' powers exactly?
This will realistically never come up again, so here is how they work.
Matchsticks (11) travels through time using fire at any point in time as a gateway. He then likes to put out the fire when he arrives, so that more copies of him from other points in time don't show up and make things complicated. Unless he wants to exploit that for battle purposes, which he clearly didn't. Scratch keeps a fire alarm in his apartment to summon him, in case it catches fire, which it clearly did.
Quarters (14) has a collection of coins like the one Clover flipped. Each has numbers on either side, corresponding to a member of the Felt, most separated by 10, with a few exceptions. i.e.
1, 11
2, 12
3, 13
4, 14
5, 15
6, 9
7, 10
8, 8
When you flip the coin, it summons the member whose number is face up, from some place in space and time. If the opposite member is present during the flip, he trades places with that member, which is why Clover swapped for Quarters when he flipped 14.
If you flip your own coin, and the result is your own number, you die. As such, Quarters entrusts his own coin with Clover, who is so lucky, he will never flip a 4. He uses it to summon Quarters when things get too hot to handle. It's not advisable to let Snowman flip her own coin.
The coins link pairs of Felt members. Some are relevant pairings, others don't make much sense. Die and Stitch have a similar power, with their destructive/healing voodoo doll and effigies. Doze and Eggs make a pair of morons with a funny duo name (dozen eggs!) Itchy runs around so fast he probably starts fires sometimes, while Matchsticks puts them out.