wher should i griend for levels if my pets are level 24 and 25.
the most resent area i have unlocked is farinas shrine.

I'd suggest the Nightfall Bandit Dungeon in the first area. The enemies are higher leveled, and stronger, so you should get better experience from beating them currently. Dungeons are made to be harder and thus should yield greater rewards and experience. You can do them once every day, and after finishing them, you can do them again the next day.
Nightfall Bandit Dungeon

i already tried that it only takes 1 batel wher i start at full health and i die i can beat all other places easily tho (exept the shrine in the fairy place i can do like 5-10 levels before i die) so im just wonderinge wher would give me the most xp that i can still win a level in : )

- Ash still has not had his proficiency point assigned

- both pets are Attacker elements, so you have no Tank (earth, water, shadow, or light) or Healer (light) element to help keep the party either defended or healed.

- Ash is an Air element (Physical/Strength-type) but has three Magical/Intelligence-type equips, including his relic

- Fia is a Fire element (Magical/Intelligence-type) but has two Physical/Strength-type equips


Setting Ash's proficiency point and altering their equips, even with no alteration to party elements, would help just by the increase to their damage output, which would in turn make grinding easier.

I'd suggest working your way through Faerina's Shrine until you either level up or reach the next area in that case.

Also, since you have access to the Sanctuary of Saerielle now, one thing that would be very helpful to you for battling is saving up gold and buying your third-party slot. You'd buy it in the Plaza. You'd press the button that says "Expand Party Max". This will allow you three party pets to use in battles, rather than just two.
Here's a link to the Sanctuary of Saerielle.

Also, another thing that will significantly help your battling is assigning the available proficiency point that your second battle pet, Ash has available;
https://www.sylestia.com/proficiency/?pet_id=7798009
Each individual pet earns Proficiency Points at levels 0, 30, 60, 65, 70, and 75, so six points in total per pet. It's important to assign those points, it will significantly strengthen your pets.

Also, since Ash is an Air pet, he should have gear that focuses on Strength and Dexterity.