Regarding the Big Plastic Flipcoins...

Espurration

I hate using them as flipcoins and see them more as collectables. If I need a flipcoin for an action in the TCG, I just use a quarter or a car wash token or something.

Nashedtators

Use a d6, heads are evens and tails are odds.

TinkaDarkrai95

For flipping a coin I enjoy using a dollar coin, or a standard coin-flip 🎲, rather than the Pokémon coins

TheJeffers

Rolling a die is definitely the way to go. The coins are okay in a pinch or for new players, but dice are more versatile, more useful and probably fairer.

I keep a range of dice in my deckboxes for use with the card games I play. D6 and D20s are great for most purposes.

clasingla

I always found the dice kind of boring and preferred the coins with Pokémon (from gen 7 and earlier gen 8’s were too big) mostly my shaymin and manaphy one

TheJeffers

A coin is just a two sided die.

OlderAngel11

I always use a die, as those are what are used in tournaments and I trust the judges. As for the coins, they are cool to collect, and sometimes I use them as ability markers when I don't feel like tilting the cards.

Nashedtators

That too, I love to show off my coins through ability use