Fast answer
Goonbug is worth building if you need stronger early wave control or want an aggressive Grass specialist that can break crowded lanes open.
Where Goonbug is best
Goonbug is strongest when:
- campaign waves are crowding your front lanes
- your board needs a higher-pressure flex slot
- you want an efficient non-premium specialist for F2P or beginner play
Evolution priority
High, but usually after the most universal S+ lines unless Goonbug is already your best practical carry.