Could you please post your species?
A freezer would be a good addition to your set. You can not yet afford a 100% freezer, but
Black Frost Cannon will be well within your budget, and has approximatly a 24% chance of freezing. You could though save up a little more for the
Entangling Lenny lasso and morph your pet to a lenny. This is the cheapest of the 100% freezers, and sells for around 2.5 million, maybe a little more, maybe a little less. Your decision will depend on how fast you can make your neopoints. I think that it might be best to go for the Black Frost Cannon at this stage, because then you can also afford a freeze bomb.
Also a good bomb will be good to go with the freezer. At your battle level, the
Honey Potion is the one to go for. This does around 14 icons, and is great for after a freeze. Replace the
stone snowball with that. Trust me, that snowball is a waste of neopoints. With cheaper alternatives out that actually do more damage than this, there is no excuse to be using it.
If you really do feel the need to use one use bombs in the battledome, then I reccomend that you use one of these ones, because they are far better value for neopoints, for what they do.
Snow Mudball,
Sticky Snowball and a slightly more expensive, but great for important battles, the
shooting star muffin. The muffin does 15 icons, and costs around 3000 Neopoints so while they are good, just save them for important battles. Just don't use those
stone snowballs
As for your pets training, you really need to train up your pets strength and defence up to nearer twice your level, otherwise you will just be paying more later with the higher level.