The coin flips in the GameBoy game are actually pre-determined before the actual flip, so you're never going to get a "fair" result. Depending on what you and/or the CPU is doing, the coin will mostly favor one or the other, especially if the actions are repetitive. For example, if your opponent keeps attaching energy cards to their pokemon before doiing the coin flip, it will ALWAYS show one side until that pattern is broken. Then a new result will happen, which is a 50/50 chance it'll be a different side.
Yoooo, you gave me an opportunity to share a funny moment I had with TCG2
So I was fighting Imakuni to get his promo card (I believe it was one of the last cards I had to get for 100% completion), and he was surprisingly kicking my butt during the fight, mainly because he was getting incredibly lucky with his Drowzee's sleep ability
After dealing with countless stall turns, he got his Meowth on the active slot and then used the "Earn Coins" attack for easy card draws (Flip a coin until tails, for each heads, draw a card)
.... And this guy just decided to draw
15 FREAKIN CARDS FROM HIS DECK
I don't have a screenshot of the aftermath, but he basically had a 22 card hand with almost no cards in the deck. I actually won because of this, by somehow unintentionally milled my opponent with a Do The Wave deck.
It was actually a huge damage nullifier. Only attacks less than 30 could damage it, so essentially something like Charmander's scratch, or you could just status it to turn it off (or give it poison to slowly zap it). Otherwise it was a literal gigantic wall against powerful cards.
There's even a hilarious TCG2 deck that I assume is based on a real competitive deck which was used for the JPN TCG tournaments.
It's a stall deck that involved Mr. Mime/Chansey, Tentacool and Alakazam.
The setup was simple: You needed to have either Mr. Mime or Chansey on the active slot.
After some turns of stalling, you would play a Alakazam to the bench to use his Damage Swap ability (arrange any damage counters from your pokemon however you like)
With the Alakazam ready, you would then play some Tentacool cards for their unique ability
So the gameplan was: Everytime you active pokemon took any form of damage, you would swap its damage counters to Tentacool, and then use Tentacool's ability to return it to your hand, which would remove all of its damage counters, and then play it back to be able to activate its ability again. You could get rid up to 80 HP worthy of damage on the best case scenario, but even one Tentacool was enough to make Mr. Mime an infinite wall.
There was some counterplay that wasn't hard to pull off, like running 4 Gust of Winds to kill the Cools (which was a great card in general), or even some status moves to disable Mr. Mime or Alakazam, but do remind that they're either tickling you to death with an unkillable Mr. Mime, or they're blocking all your damage every few turns with a Chansey using a lucky Scrunch.