You get the option from 3 starter packs "Powerful" "Balanced" "Maniac"
I personally chose Maniac
Each of your 3 Digimon has 3 different evolutions you can achieve fairly quickly and you can get new digimons later but that's gonna take awhile that's why it's important to chose a starter pack that fit your needs.
Digimon or not this is just a good well made rpg game, it's one of those games you can roam anywhere pretty much from the start, like the pokemon games it gives you the freedom to go everywhere BUT unlike those games, you don't really need to talk to every Npc to progress and you dont need "cut" for silly obstacles, you can wherever you like and the story unfolds as you do, it's pretty great.
The only flaw i see in this game is that the evolutions are kinda just handed to you too quick.
you'll grind happily to get them but once you do the excitement is kinda over and getting new digimons aint that easy