Get a turkey of high level and a strong level 23+
"sandwich" the level one between them
Turkey - slot 1
lowbie pet - slot 2
strong lv23+ - slot 3
when battle starts use the turkey "food comma" attack, put the level 23+ enemy to sleep. Swap to slot 2, put your lowbie pet. you don't even need to attack it, just pass.. swithc to slot 3, your strong battle pet. Kill all 3 enemies. Gain 4 levels.. profit!