Your team looks good, but Donphan doesn't have a nature. I'm testing your team with Donphan having the adamant nature. I will let you know if I learn anything from the testing.
After a few battles, I noticed that your team has trouble with water types. Half your team is weak against it, which is fine. However, Arcanine is really the only one that can do a lot of damage to them, and a switch is too risky. I would recommend giving Chesnaught Seedbomb instead of Spikes. A grass move would help a lot and I've always found Spikes to be less important than Stealth Rock. Also I would recommend replacing Suicune's Sleep Talk with Hidden Power Grass or Electric and giving it a Chesto Berry to hold. The set you have for it seems to be a favorite, so this change may help. Let me know if you have any questions.