The weight is probably an issue and as it's so high I'm guessing you don't play any games with it either, so it's skill points remain low? If it's skill points (the pencil, the flower and the star) are high, you're more likely to get specific characters rather than universal, but they may still occur. Your Tamagotchi's adult character also depends what type of toddler/teen they are. It's worth looking at a V4 growth chart for all this information.