Palkia is IMO the best one to take. It is in IQ group J, which has the best skills. Stair Sensor / Map Surveyor / House Avoider / Absolute Mover. Energy Saver is also incredibly useful.
Kyogre is very useful due to his great stats.
Mew can use Transform, being super helpful here.
Kecleon is also very amazing. Harder to recuit than use in DTower.
Dialga is great. IQ group I. Many resistances.
Metronome Users work well. Specifically Snorlax.
Lucario does not work too well. IQ and weaknesses are important. One type Pokemon are edgy, unless special conditions.
And my source is running through this tower with every Pokemon.