This is likely where you will run into the most issues adapting your game to CD10, as CD10 is designed largely to facilitate combat between somewhat equally sized and skilled opponents. While party of players in Dungeons and Dragons could defeat a dragon, given proper equipment and levels, it would be virtually impossible for the same party to defeat something as massive as a dragon in CD10. It's simply not that kind of game.
Fighting giant beasts
If your campaigns focus a lot on giant monsters and massive feats of martial prowess against colossal monstrosities, you might either want to look towards a system better suited for that kind of gameplay, or be creative in how you design your campaigns. It is still very much possible to make such stories in CD10, but they become more about the preparation for the encounter, rather than about the final fight itself. The final fight can certainly be epic in narrative scale, but the preparations the players have done, leading up to that fight, are more important than the fight itself.
The campaign should be about the party gathering allies and performing adventures to reduce the power of the final "boss", so that they have a decent chance to fight it. Even so, the final confrontation shouldn't be determined purely by combat rolls, but about choices and the preparation that has been done to lead up to this moment.
Why? Because in CD10, any giant monster is just going to decimate even an insanely experienced party. Without something to even out the balance, the pure, unadultered power of a colossal beast is going to turn a party to mush in no time. Imagine a group of highly trained medieval knights trying to defeat a tyrannosaurus rex that can breathe fire, and you have some idea of where we're going. Hence the need to be a little bit creative if you need such beasts in your campaigns in CD10.
All bets are off
When we're moving away from playable creatures in CD10, all bets are off as far as limitations go. No longer need you stick to a 0 add-up for traits, -4 to +4 is no longer a limitation on traits and skills can go higher than 12 if needed. A bear can easily have Big +8 and for such beasts, you may even add in traits that further enhances their physical abilities, something we discourage for player characters. So if you need an enormously strong creature that isn't necessarily huge, you may add a trait called Strong and put it at +10 or something, adding pure damage to it's mauling strikes.
Designing monsters is less a balancing act than characters, but you must also keep in mind that while these beasts can be much more powerful than a player character, they are also fully capable of completely dumpstertrucking a party if you overtune them. Getting hit by the above beast would have a minimum lethality of 10, not counting claws or excess from the attack roll. That's going to hurt no matter who you are or what you're wearing.
Skills and traits
It's a common practice to either grant large, singular monsters free actions through traits, or put their skill cap very, very high so they can stress multiple times in a turn without becoming useless. This is so that a creature can fight multiple party members at once without instantly becoming useless.