Well i mean if botamo can negate damage because of his dimension. Theoritically he could be unaffected by Beerus'/Champa's attacks. Unless Beerus'/Champa's punch can blow up his dimension. Remember Champa was gonna kill all of his fighters for losing the tournament against beerus. Claiming that none of what they have can stand up to him.
Also since botamo uses it to send attacks to it. Magic isn't the same, Magic attacks the user's mind and changes their phyiscal conception as a whole. From what i've seen botama dimension only works to a certain point on his body not his whole body at once. If he got swallowed by a big kamehameha not like the one goku used that only hit his belly.
Like this one how could he deflect that?