Magma Cavern B3F. Trust me I saw and beat him.
I believe if you look at red rescue team it is the same.
after you defeat groudon
you fight off groudon and kygore
-10%
You may recruit Groudon after the end credits of the game.
magma cavern pit 3floor
magma caverns
groudon
try to use a water type Pokemon because of typeadvantage
Moltres, Zapdos, Articuno, Groudon, Kyogre, Rayquaza, Deoxys, Mew, Celebi, and a few others.
From Wish cast after you defeat groudon in the magma cavern. Hope it helped:)
You can rescue Alakazam's team in Magma Cavern where you defeat Groudon That is the only place I have rescued them so far because i havent beat the game yet