Anything matching the Pokemon on his team.

He's biased like that. Might as well have the complimentary set.

Avian doesn't tend to treat himself but maybe the Deino line. Possibly Volcarona

Stahl would buy them all then donate/give them away.

Arryn: All the legendaries.

Ironically, I’ve already watched that video and I’d say Mel would either get Oshawott, Tepig, Simisear or Roggenrolla