Grover's axes do so much damage at long range, that Grover can potentially have more damage-per-second than Kinessa at a certain point, making him a strong option for dealing with her at a distance.
If Fernando doesn't have his shield up, try to hit him with your spit (don't detonate it). After it hits, you do more damage to him with your rockets, taking him down faster.
Encountering Grover in long range open spaces - don't PEEK around the corner.
Good Grover players throw axes preemptively and you can take a lot of damage. Use short sprints between cover. This way it's harder to predict where to aim.