None of them are. He doesnt' change teams in Challenge mode.Ripped the rival battles because used Google Translate to make Rival in Japanese and ctrl + f'd this source for the battles and translated the pokes: http://pokebook.jp/data/bw2/trainers.html No locations, sorry.
Rival Battle #1:
Lv. 5 Tepig
Lv. 5 Snivy
Lv. 5 Oshawott
Rival Battle #2:
Lv. 8 Tepig
Lv. 8 Snivy
Lv. 8 Oshawott
Rival Battle #3:
Lv. 20 Pignite | Lv. 18 Pidove
Lv. 20 Servine | Lv. 18 Pidove
Lv. 20 Dewott | Lv. 18 Pidove
Rival Battle #4:
Lv. 33 Pignite | Lv. 31 Simipour | Lv. 31 Tranquil
Lv. 33 Dewott | Lv. 31 Simisage | Lv. 31 Tranquil
Lv. 33 Servine | Lv. 31 Simisear | Lv. 31 Tranquil
Rival Battle #5:
Lv. 39 Unfezant | Lv. 39 Simipour | Lv. 41 Emboar
Lv. 39 Unfezant | Lv. 39 Simisage | Lv. 41 Samurott
Lv. 39 Unfezant | Lv. 39 Simisear | Lv. 41 Serperior
Rival Battle #6:
Lv. 43 Emboar | Lv. 41 Simipour | Lv. 41 Unfezant
Lv. 43 Samurott | Lv. 41 Simisage | Lv. 41 Unfezant
Lv. 43 Serperior | Lv. 41 Simisear | Lv. 41 Unfezant
Rival Battle #7:
Lv. 50 Emboar | Lv. 48 Simipour | Lv. 48 Unfezant
Lv. 50 Samurott | Lv. 48 Simisage | Lv. 48 Unfezant
Lv. 50 Serperior | Lv. 48 Simisear | Lv. 48 Unfezant
Rival Battle #8:
Lv. 55 Unfezant | Lv. 55 Simipour | Lv. 55 Bouffalant | Lv. 57 Emboar
Lv. 55 Unfezant | Lv. 55 Simisage | Lv. 55 Bouffalant | Lv. 57 Samurott
Lv. 55 Unfezant | Lv. 55 Simisear | Lv. 55 Bouffalant | Lv. 57 Serperior
I don't know what is challenge mode and what isn't, but there.
He also has 2 other battles you missed that show up in the post game.