From what I could gather, the Pizza guy starts at 0.25 Tons and grows to 0.57 Tons after the transformation while Dante in his DT form upscales from 0.83 Tons, so Dante should have a decent AP advantage here by over 3.32x and then over 1.45x. The enemies he summons in the first phase aren't exactly strong, so it doesn't really matter for Dante, and I was told he can only use his regen once.
It's about 5 or so enemies per summon, but Dante can fight a dozen of enemies without ever getting hit, so they wouldn't be a problem, and he can likely ignore them since he can fly. If the pizza guy can transform in time, them it's still pretty similar. The enemies he summon apparently scale to about >0.13 Tons, which means they are easily dispatched by Dante as well. Once again, none of them are particularly skilled and coupled with the huge AP advantage and regen from Dante, he wouldn't have a problem with any of the summons in either form.
Against the Pizza guy himself, the first form it seems like it can only ram itself, so it wouldn't be hard taking it out to have it move to its next form, and that one isn't very formidable either, the Danmaku is not too impressive and Dante can likely just regenerate from it, getting close shouldn't be too hard with Dante's acrobatics and flight. Pizza Guy has regen, but so does Dante, and Dante's regen is better and in CQC Dante has the clear advantage as the Pizza guy doesn't seem to be skilled in any way. Pizza Guy's acrobatics doesn't seem as impressive as Dante's either, so that's also another point for him. His after images don't really seem like something noticeable to talk about, his shockwave only seems to make someone fly from the ground and don't damage, which doesn't really affect Dante, who can innately fly while his Explosion manip shouldn't do anything either.
His last 3 abilities, the curse related ones, doesn't seem like something he can use in combat either, so that wouldn't come up. Looking at his weaknesses, he seems to take fights not that seriously, Dante likes to quip, but he can also get serious when needed, especially when he is in his DT form. Dante would not go easy on him either due to the Pizza guy not being a human and last, but not least, you also have their LS, which Dante also holds an advantage of over 20x
TLDR, I would vote Dante due to better Regen (High-Low vs Low), better Acrobatics, AP advantage (>1.45x), LS advantage (>20x) while also being a skilled fighter. The summons shouldn't pose any threat due to Dante's massive AP advantage over them (Which is over 6x) and their unskilled nature