for this combo you will need
fishborg - gunner (field or grave)
card of safe return
mass driver
one or more lv 3 or lower water tipe monster on the field

relies gunner for 400 with mass driver
discard one to bring fishborg back
draw one card do to card of safe return
relies gunner for 400 with mass driver
discard one you get the idee you just need 20 cards in your deck to win

fishborg can be played easely with foolich or one for one
card of safe return can become a problem is it limitit here or 3

you can olsow yous this with all sorts of cards that require a tribute
the best deck for this is frog deck cous it is full of lv 2 water types and one for one is a good card in that deck and you can olsow yous the combo with substitoad if you don't have mass driver (5 free frogs + a hand shuffel )

one more combo

Witch Doctor of Sparta:
flict 500 damage to your opponent each time a monster(s) is Special Summoned from either player's Deck.

substitoad:
Tribute 1 monster to Special Summon 1 "Frog" monster from your Deck, (except "Frog the Jam"). "Frog" monsters (except "Frog the Jam") cannot be destroyed by battle.

1 random monster on the field

releas the random monster for substitoad and witch will do 500 than you tribute the new frog and repeat the proses

you get the idee evry frog in the deck becoms a 500 point bullit

For the 1st combo note that Fishborg Gunner is not yet available in TCG (OCG only), and the combo also relies on a limited card (CoSR) which doesn't really have much business in a Fish deck outside of that OTK. Additionally, Fish just aren't quite good enough at milling through the deck to get the cards needed for this OTK very consistently, so attempting this in a real duel is somewhat difficult.

Witch Doctor combo is difficult to pull off simply because it requires 3 monsters on the field. Also, although it is a good combo it is only an LP damage combo that doesn't give any particular field advantage and I don't think you're gonna be able to summon 16 times with Substitoad so it is limited in the amount of damage it can do as well.

Overall, your combos aren't bad, they're just both very difficult to pull off in an actual duel setting.

well for witch doctor of sparta it is not that difficult just play summener monk and you have a random monster and wich doctor and I dont see wy you cant do that 16 times if you build your deck with cards like pot of averice.