Ash's Swellow

ash catch a tailow in his journey this is what happened. they saw a whole bunch of tailow then it attack them and ash pikachu can't defeat them until they gone and team rocket saw them and they told them that get pikachu. well tailow and pikachu battled and pikachu really can't defeat that tailow but pikachu makes it really tired. brock told to ash that why does he just catch that tailow to stop the battle even though that tailow is tired because of pikachu then ash throw a pokeball and he catched it