Sharing my luck

In my opinion there are varying degrees of “powering up”. Example: I have a 100% Gardevoir that is maxed. 100% dark Tyranitar maxed. 100% Blaziken...level 30. 100% regular Gyarados...level 30. 100% Victreebel...level 30. 100% regular Muk...level 15. 100% Kingler...level 15.

Your Blaster:
Sunglasses, check.
Hydro cannon, check.
Shiny, check.
100%, check.

I’d initially take it to level 30 without much worry. Beyond that, I’d develop a baseline of stardust reserve and only spend on frilly things when you are above that baseline.

Give it to me and it will be 40 in 5 minute :)

Blastoise sucks (comparable to Vaporeon if it has Hydro Cannon, iirc), its shiny form is ugly and so are its sunglasses. It's a very big no for me, until I have maxed out 6+ of the top 3 of each type and less ugly 100% and/or shiny Pokémon.

But to each their own, I guess

You seem happy and proud about it. That is probably What matters most. Dont get hung up on DPS and IV only.

Take it to lvl 30 and Use it as a gym battler imo. I got a lvl 30 lanturn double electric that I Use cleaning and Holding gyms. Not the best Pokémon but i like lanturn.

Did you really? That is so amazing!! Do it if you want, it might not be as relevant as others, but that should not be a barrier to enjoy him

Use it as a Gym Sweeper. Hydro Cannon is miles ahead of it's two bar counterpart Water Pulse, (More damage, better cool down) Even though it's worse than Vaporeon running Hydro Pump, it is better than the Aqua Tail set, and therefore, it's usable. Certainly better than Starmie, Golduck, the Slowdudes, and Omastar. (Not sure about Milotic)

I’m shocked that no one mentioned the obvious forthcoming mega evolutions. I’m not sure I would power it up yet because we don’t know how Megas will work, but you’re going to have the best Blastoise available.

I would with MY stardust count.
With yours... I'd hold on