I think it would be good to have a training mode, a battle mode with no rewards, either pve or pvp, but that is based around the level of dinosaurs in your current team. Also allow us to pick some of our 4 dinosaurs, if not all for this game mode.
An example of what this would achieve, yesterday I wanted to try out a whole new team setup with impact and runs with SIA. I only have level 11 - 12 of these dinosaurs, except for the lvl 15 stygy. I usually in battle arena face with a team of 5 lvl 15s, 1 level 16, 1 level 17 and 1 level 13, mostly an enemy team with levels 19 - 22, which in itself is a problem, but I guess its based on the number of trophys I have. But currently due to strike towers being a fixed layout and way too easy, arena is the only place I can test out a new team setup, so I had 4 lvl 11s, 3 lvl 12s and 1 lvl 15, and I was still against the same lvl 19 - 22s. So I can’t test our my new team setup, and even then, I would get 4 dinosaurs that don’t really allow me to test the whole strategy of my team (I feel like if you use SIA, you have to build a whole deck around it), because I kept getting the wrong dinosaurs. If I were to actually use this setup, I would have enough dinosaurs by then to use this strategy. But the problem is, I cannot see how this strategy would fair if I am unable to properly test it. This is the same as if you want to try a new dinosaur too, to see how well it would fit in. So therefore, I think a training mode would be a really good addition.