Chaos Dragons also bring the addition of far more defensive plays using Red-Eyes Darkness Metal Dragon and Lightpulsar, which is advantageous against a lot of decks
Dark Raichu #7 (Pokemon Legendary Collection | Pokemon Cards) prices are based on the historic sales
Of course, look at the buylist price of that card relative to the next two
Mishra wouldn't show up as a normal card until years later in Time Spiral when he finally got a legendary creature card
(2) The other pro is that giving your opponents more cards in situations where one of your opponents is in the lead makes it much easier for the table to gang up on them and set them back, and in situations where you're in the lead you can simply choose not to ring the bell just to maintain your advantage
If you think you have one of these rare holographic, gold star, or base set cards, then the first step to take before even thinking about selling them is getting the cards professionally graded