portals:

starting region analysis: water or ground for mudkip for water 3 opener dragon region is helpful for finding dragons to generate a portal

t10 fossil 2/8 for dracovish, dracozolt monster 1/4 for druddigon grass 1/6 for applin fire 1/6 for turtonator aquatic 1/6 for dracovish normal 2/15 for cyclizar, drampa wild 1/8 for druddigon steel 1/9 for duraludon gourmet 1/9 for applin electric 1/12 for dracozolt psychic 1/15 for latios/latias

t20: fossil 3/8 (4/9 if walking wake region) for eternatus, regidrago, roaring moon, walking wake ground 1/3 for zygarde ice 1/4 for kyurem water 1/5 for palkia (2/5 if walking wake region) monster 1/5 for regidrago ghost 1/5 for giratina light 1/5 for necrozma dark 1/5 for roaring moon (1/6 with regional moltres?) electric 1/6 for zekrom poison 1/6 for eternatus fire 1/9 for reshiram psychic 1/10 for necrozma (1/11 with regional articuno?) steel 1/11 for dialga flying 1/12 for rayquaza