So if I purchase say strength for (250) exp, does that exp go straight onto my pet or do I have to somehow use it? Thanks!

If you spend 250exp on strength for that pet, its strength goes up by 1 point.

I see, they actually just updated so I see them now. Do you recommend saving them until later tiers?

If you want to use them earlier, I suggest you use them on level which costs less, or wait until you max out training that stat for the current training time tier. You'll end up earning and spending them at Tier 10+ anyways, but just try to use them before T13 where the costs triple (For example, level cost 3000exp instead of 1000exp)

I see, well thanks for all the help :)