My thoughts about that:
For the first sea:
1- Light fruit: High speed, great damage, good AOE, not so hard to get, not so hard to master, and it's also good for grinding even in the first half of the second sea.
2- Magma fruit: Easy to grind, high damage, medium AOE, a bit hard to get in comparison to other fruits.
3- Ice fruit: Medium range, good stuns, above average AOE, easy to get.
Tips to get fruits in the first sea: Grind Bobby and keep an eye on the stock to get those fruits.
Don't use hard mastery fruits in the first sea, EXCEPT BUDAH. If you get Budah, you can use it until the third sea if you want.
For the second sea:
1- Blizzard fruit: Even if it's hard to get, it's all worth it. Humongous AOE (super useful to gather a lot of enemies together). There is a super useful combo to kill even 6 enemies if they are really close together: V, then a few jumps to avoid the enemies' attacks, then X when they get near you, right after C move to fasten them, and then you can finish all of them with the Z move. Even if one of them escapes, you can finish them with the F move.
2- Budah: Great for grinding, use alone or in a group. Use only if you are a fighting style user or a sword user. Get big and use anything else but the Budah attack.
3- Love fruit: Good AOE attacks, great damage. Besto Friendo is super useful to finish enemies and even to grind using only the Besto Friendo. He can kill 2 enemies depending on your level.
For the third sea:
(Focus on upgrading your main fighting style to the max)
1- Blizzard fruit: Same reasons as before.
2- Budah: Same reasons as before.
Good grinding!
