[Pet]

You play Rainbowtail too? Cool!
I am stuck in a level though, i don't have very rare gemlings, i have basic ones, like Frooma and that spider-looking gemling i forgot the name of.

Would you mind to tell me which level you're stuck in?
And it must be Helizap or its pre evos Bomzing or Bomchub, it may be good to stun boss to stop producing obstacles until it's gone and its pretty high basic movements also help the you to damage them without being wasted. But its low attack isn't good for those with high hp or defs and I recommend you to using Cactos or F.Cactos if you need a Gemling with Stun trait.
Well, the Very Rare Gemlings usually can be farmed through Material Quests including where drops Soul Gemlings and most of them are pretty useful and easy to level them up due to able to farm them without spending dozens of Gembeans for either pulling free draws or buying in Shop.

If you're looking for good levels to farm Gembeans, I recommend you to run Herbling Material Quest or 5-3 Belly of the Beast.